REF ODBC John Gibson Aug 1996
COPYRIGHT University of Sussex 1996. All Rights Reserved.
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<<<<<<<<<<<<<<<<<<<<< POPLOG INTERFACE TO >>>>>>>>>>>>>>>>>>>>>
<<<<<<<<<<<<<<<<<<<<< OPEN DATABASE CONNECTIVITY >>>>>>>>>>>>>>>>>>>>>
<<<<<<<<<<<<<<<<<<<<< >>>>>>>>>>>>>>>>>>>>>
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CONTENTS - (Use <ENTER> g to access required sections)
1 Introduction
2 Differences from the C Interface
2.1 Procedures
2.2 INCLUDE ODBC
2.3 SQL Data Types
2.4 Pop Data Types
2.5 Environment, Connection & Statement Handles
3 Data Input/Output Modes
3.1 false (Pop Value Mode)
3.2 3-Element Vector (Byte Buffer Mode)
... Input
... Output
3.3 Procedure (Byte Stream Mode)
... Input
... Output
3.4 Special Data Values
... NULL Values
... Default Parameters in SQL Procedure Calls
3.5 Extended Fetch and Update
... Pop Value mode
... Byte Buffer mode
... Byte Stream mode
... Unfetched Rows
4 Connecting to a Data Source
5 Driver/Data Source Information
6 Driver Options
7 Preparing SQL Requests
8 Submitting Requests
9 Retrieving Results & Result Information
10 Data Source System Table Information
11 Terminating Statements & Connections
12 Asynchronous Statement Processing
13 Examples
13.1 Static SQL
13.2 Ad Hoc Query
... Using sql_app_result_set
---------------
1 Introduction
---------------
LIB * ODBC is a Pop-11 interface to Microsoft's ODBC (Open DataBase
Connectivity), a C language API which allows applications to access
database management systems using Structured Query Language (SQL).
Before using any procedures, the library must be loaded with
uses odbc;
The include file INCLUDE * ODBC defines various integer constants
and macros for use with these procedures:
include odbc.ph;
LIB ODBC assumes Extension Level 1 conformance from all drivers. It
implements all Core and Level 1 functions, and (currently) all Level 2
functions except the following:
SQLParamOptions
SQLMoreResults
SQLProcedures
SQLProcedureColumns
This file describes only the Pop interface to ODBC, and does not attempt
to provide a tutorial on ODBC in general. The description of LIB ODBC
procedures should therefore be read in conjunction with ODBC
documentation for the C interface.
In all cases, the descriptions of the Pop procedures indicate which C
functions they call. Where a Pop procedure is dependent on a Level 2
function, * sql_connect_functions can be used to test whether the
particular driver supports that function or not.
-----------------------------------
2 Differences from the C Interface
-----------------------------------
2.1 Procedures
---------------
LIB ODBC is a Pop-paradigm implementation of the C interface, rather
than a literal one. Thus while the Pop procedures are roughly comparable
to the C ones, they are by no means identical.
For this reason, the Pop procedures have all-lowercase names starting
with sql_, e.g. sql_bind_parameter rather than SQLBindParameter. (The
Pop names are also generally cleaner and more explicit. In particular,
the names of all procedures that return data by creating a result set
begin with sql_select_.)
Unlike the C functions they call, LIB ODBC procedures do not return
status codes: they either return nothing, or (where appropriate) return
data values directly.
Instead, when a LIB ODBC procedure calls a C function which returns an
error (return code SQL_ERROR), the Pop procedure will raise a mishap
with sys_raise_exception. If a function returns SQL_SUCCESS_WITH_INFO,
the Pop procedure will raise a warning and continue. In both cases, the
exception message text is obtained from SQLError, and the exception has
an id-string of the form
odbc-funcname:exsys-odbc-sqlstate
where funcname is the name of the C function being called and sqlstate
is the SQLSTATE returned by SQLError.
All other C return codes are handled automatically by LIB ODBC. (The
only procedure which effectively hands on a C status result is
sql_fetch, whose true/false result corresponds to
SQL_SUCCESS/SQL_NO_DATA_FOUND from SQLFetch.)
The following table summarises the LIB ODBC equivalent of each ODBC C
function:
C Interface LIB ODBC
----------- --------
SQLAllocConnect Called automatically by * sql_connect.
SQLAllocEnv * sql_environment if required, but called
automatically by * sql_connect.
SQLAllocStmt * sql_alloc_statement.
SQLBindCol * sql_bind_column.
SQLBindParameter * sql_bind_parameter.
SQLBrowseConnect * sql_connect.
SQLCancel Assigning false to * sql_statement_busy for
a statement.
SQLColAttributes * sql_column_attribute.
SQLColumnPrivileges * sql_select_column_privileges.
SQLColumns * sql_select_columns.
SQLConnect * sql_connect.
SQLDataSources * sql_data_source_repeater.
SQLDescribeCol * sql_describe_column.
SQLDescribeParam * sql_describe_parameter.
SQLDisconnect * sql_disconnect (or GC destroy action).
SQLDriverConnect * sql_connect.
SQLDrivers * sql_driver_repeater.
SQLError Called automatically for message strings
when an exception is raised.
SQLExecDirect * sql_execute with optional SQL string.
SQLExecute * sql_execute.
SQLExtendedFetch * sql_extended_fetch.
SQLFetch * sql_fetch.
SQLForeignKeys * sql_select_foreign_keys.
SQLFreeConnect * sql_disconnect (or GC destroy action).
SQLFreeEnv GC destroy action.
SQLFreeStmt * sql_free_statement (or GC destroy action).
SQLGetConnectOption * sql_connect_option.
SQLGetCursorName * sql_cursor_name.
SQLGetData Called automatically by * sql_fetch and
* sql_extended_fetch.
SQLGetFunctions * sql_connect_functions.
SQLGetInfo * sql_connect_attribute.
SQLGetStmtOption * sql_statement_option.
SQLGetTypeInfo * sql_select_types.
SQLNativeSql * sql_native_sql.
SQLNumParams * sql_num_parameters.
SQLNumResultCols * sql_num_result_columns.
SQLParamData Called automatically by * sql_execute and
* sql_set_position when necessary.
SQLPrepare * sql_prepare.
SQLPrimaryKeys * sql_select_primary_keys.
SQLPutData Called automatically by * sql_execute and
* sql_set_position when necessary.
SQLRowCount * sql_row_count.
SQLSetConnectOption * sql_connect_option updater.
SQLSetCursorName * sql_cursor_name updater.
SQLSetStmtOption * sql_statement_option updater.
SQLSetPos * sql_set_position.
SQLSpecialColumns * sql_select_special_columns.
SQLStatistics * sql_select_statistics.
SQLTablePrivileges * sql_select_table_privileges.
SQLTables * sql_select_tables.
SQLTransact * sql_transact.
2.2 INCLUDE ODBC
-----------------
The file INCLUDE * ODBC defines a similar set of macros for integer
constants as the corresponding C header file 'sql.h'.
However, whereas in C all these macros have names beginning with SQL_,
in LIB ODBC some begin with Sql_. In all cases, Sql_ values are the
corresponding SQL_ values shifted left 16 bits, with extra information
encoded in the bottom part.
(If required, the inline macro SQL(Sql_value) can be applied to an Sql_
value to get the SQL_ value, e.g.
SQL(Sql_INTEGER)
is SQL_INTEGER. Note that in general, INCLUDE ODBC defines either the
Sql_ or the SQL_ value, but not both.)
Most of the Sql_ values are input arguments to the procedures
sql_connect_attribute, sql_connect_option, sql_statement_option and
sql_column_attribute, where they specify a particular attribute or
option (and where the bottom 16 bits encode the data type of the
corresponding attribute/option value).
2.3 SQL Data Types
-------------------
ODBC SQL data types describe the represention of data by the driver. In
LIB ODBC, they are Sql_ values in which the bottom 16 bits encode the
precision and the scale of the type, and additionally, a bit to
differentiate between signed and unsigned for integer types.
The LIB ODBC SQL types are listed below, together with the corresponding
default Pop type for each (see next section).
For types whose precision and scale are variable, the Sql_ definition is
not a single value, but an inline macro that takes one or two
parameters. These are
SQL Type Default Pop Type
-------- ----------------
Sql_CHAR(nbytes) Sql_P_string
Sql_VARCHAR(max_nbytes) Sql_P_string
Sql_BINARY(nbytes) Sql_P_binary
Sql_VARBINARY(max_nbytes) Sql_P_binary
Sql_NUMERIC(precision, scale) Sql_P_string
Sql_DECIMAL(precision, scale) Sql_P_string
The non-parameterised types are
SQL Type Default Pop Type
-------- ----------------
Sql_BIT Sql_P_boolean
Sql_TINYINT Sql_P_sbyte
Sql_SMALLINT Sql_P_short
Sql_INTEGER Sql_P_int
Sql_BIGINT Sql_P_longlong
Sql_REAL Sql_P_sfloat
Sql_FLOAT Sql_P_dfloat
Sql_DOUBLE Sql_P_dfloat
Sql_DATE Sql_P_date
Sql_TIME Sql_P_time
Sql_TIMESTAMP Sql_P_timestamp
Sql_LONGVARBINARY Sql_P_binary
Sql_LONGVARCHAR Sql_P_string
The types Sql_TINYINT, Sql_SMALLINT, Sql_INTEGER and Sql_BIGINT indicate
signed integers, and each has a corresponding unsigned version:
SQL Type Default Pop Type
-------- ----------------
Sql_UTINYINT Sql_P_byte
Sql_USMALLINT Sql_P_ushort
Sql_UINTEGER Sql_P_uint
Sql_UBIGINT Sql_P_ulonglong
The above SQL type encoding simplifies the arguments to
sql_bind_parameter, by condensing three of the arguments to
SQLBindParameter into one (also three SQLDescribeColumn results into one
sql_describe_column result, etc).
The signed/unsigned distinction for integer types makes it unnecessary
to specify an explicit Pop type to sql_bind_parameter merely for the
purpose of indicating signed or unsigned.
Note that the parameters to types like Sql_CHAR are evaluated at
compile-time, and cannot be run-time expressions. The following
procedures may be used to manipulate SQL type descriptors at run-time:
sql_cons_sql_type(stype, precision, scale, unsigned) [procedure]
-> sql_type
Constructs a LIB ODBC SQL type descriptor sql_type (an integer).
stype is the basic ODBC SQL type; precision and scale are the
precision and scale of the type. precision must range from 0 to
255, and scale must range from 0 to precision.
unsigned is a boolean which if true indicates that an integer
type (i.e. stype = SQL_TINYINT, SQL_SMALLINT, SQL_INTEGER or
SQL_BIGINT) should be considered unsigned rather than signed.
(unsigned is ignored for other types.)
Note that an sql_type descriptor for a long data type (stype =
SQL_LONGVARCHAR or SQL_LONGVARBINARY) does not represent the
maximum number of bytes allowed for the type (since this is
likely to be a large number such as 2**31-1). Hence in this
case, precision is ignored and set to 0 (and scale must be 0).
sql_dest_sql_type(sql_type) [procedure]
-> (stype, precision, scale, unsigned)
Given a LIB ODBC SQL type descriptor sql_type, returns the
four component fields of the type.
The following code fragment illustrates the use of sql_dest_sql_type
(and the SQL inline macro) to perform a go_on on the basic type of a
given sql_type descriptor:
sql_dest_sql_type(sql_type) -> (stype, precision, scale, unsigned);
go_on stype to SType:
SType SQL(Sql_CHAR(1)):
SType SQL(Sql_VARCHAR(1)):
SType SQL(Sql_BINARY(1)):
SType SQL(Sql_VARBINARY(1)):
<some code>
goto SType end;
SType SQL(Sql_TINYINT):
SType SQL(Sql_SMALLINT):
SType SQL(Sql_INTEGER):
SType SQL(Sql_BIGINT):
<some code>
goto SType end;
SType SQL(Sql_REAL):
SType SQL(Sql_FLOAT):
SType SQL(Sql_DOUBLE):
SType SQL(Sql_DECIMAL(1,0)):
SType SQL(Sql_NUMERIC(1,0)):
<some code>
endgo_on;
(Note that for the above, the parameterised Sql_ types can use any legal
parameter values, since the basic stype is not affected.)
2.4 Pop Data Types
-------------------
In the C interface, the ODBC C data types specify the representation of
data required in the application program; when data is transferred, the
driver converts data between this representation and the SQL type
representation. Each SQL type has a corresponding default C type.
In LIB ODBC, the role played by ODBC C data types is played instead by
Sql_P_ Pop data types (the SQL() values of which are the C types they
correspond to). Each SQL type has a corresponding default Pop type (see
previous section).
Unlike the C interface, LIB ODBC provides three different mechanisms for
actually accessing data -- see Data Input/Output Modes below.
The Pop data types are
Sql_P_boolean
Sql_P_bit
Sql_P_sbyte
Sql_P_byte
Sql_P_short
Sql_P_ushort
Sql_P_int
Sql_P_uint
Sql_P_longlong
Sql_P_ulonglong
Sql_P_sfloat
Sql_P_dfloat
Sql_P_bookmark
Sql_P_date
Sql_P_time
Sql_P_timestamp
Sql_P_string
Sql_P_binary
The types Sql_P_sbyte through Sql_P_dfloat represent storage locations
as for a Pop record field of the corresponding type (see Field
Specifiers for Poplog Data in REF * KEYS).
The type Sql_P_bit is the same as Sql_P_byte, except that only the
bottom bit is significant; Sql_P_boolean is the same as Sql_P_bit,
except that the bit value is converted to/from a boolean in Pop value
mode (see Data Input/Output Modes below).
Sql_P_bookmark is the same as Sql_P_uint (note that this is the default
Pop type for * sql_bind_column on column number 0).
Sql_P_date, Sql_P_time and Sql_P_timestamp represent storage locations
for the i_typespec structures sql_date, sql_time and sql_timestamp
defined in INCLUDE * ODBC.
The types Sql_P_string and Sql_P_binary both represent storage locations
for data as a sequence of bytes. (In the C interface, these two types
must be distinguished, because of null-termination for strings. In the
Pop interface this does not apply, and the only difference between them
is that for input to non-LONG parameters (i.e. excluding Sql_LONGVARCHAR
or Sql_LONGVARBINARY parameters), Sql_P_string implies a maximum length
of 254 bytes rather than 255 for Sql_P_binary.)
2.5 Environment, Connection & Statement Handles
------------------------------------------------
In LIB ODBC, the C-interface handles for the environment, connections
and statements are packaged as external-pointer class records (whose
contents are otherwise opaque to the user).
Each record is given a garbage collector destroy action, which will be
called when the record becomes garbage.
Since there is only one environment handle, this is never explicitly
required as an argument to any procedure. It is created automatically by
* sql_connect if necessary, but may be explicitly created by referencing
the active variable * sql_environment.
--------------------------
3 Data Input/Output Modes
--------------------------
The DATA_BUFF argument to sql_bind_parameter specifies how data for a
parameter is input when sql_execute is called. (It also specifies how
data is output for an output parameter in an SQL procedure call, i.e. an
SQL call statement that calls a named executable object defined by the
data source.)
Similarily, the DATA_BUFF argument to sql_bind_column specifies how
data for a column is output when sql_fetch is called.
In both cases, DATA_BUFF represents either one or two arguments: a
single identifier record main_id, optionally followed by a second item
mode.
The mode item controls the mode in which data is transferred, and may be
# false (the default if omitted);
# a 3-element vector;
# a procedure.
Alternatively, mode may be another identifier whose idval will contain
one of those three at the time of the sql_execute or sql_fetch. (In
other words, mode may be supplied as a bind-time constant, or through an
identifier whose value can change between calls to
sql_execute/sql_fetch.)
The different modes (in order of increasing complexity) are as follows:
3.1 false (Pop Value Mode)
---------------------------
When mode is false (or omitted), the data value is simply a Poplog
object input from, or output to, the idval of main_id.
The Pop types Sql_P_sbyte through Sql_P_dfloat accept as input any item
that can be assigned into a Pop record field of that type, and produce
as output the result of accessing such a field.
An input value for Sql_P_bit must be either 0 or 1, with the same
produced on output; for Sql_P_boolean, the truthvalue of an input item
is converted to 0 or 1 (0 for false, 1 for anything else), and output
produces false or true.
The types Sql_P_string and Sql_P_binary both accept or produce a string.
The Pop value corresponding to the Sql_P_date, Sql_P_time and
Sql_P_timestamp types is a full vector whose first element is the word
"sql_date", "sql_time" or "sql_timestamp", and whose remaining elements
are integers:
Type Vector
---- ------
Sql_P_date {sql_date year month day}
Sql_P_time {sql_time hour minute second}
Sql_P_timestamp {sql_timestamp year month day
hour minute second fraction}
3.2 3-Element Vector (Byte Buffer Mode)
----------------------------------------
When mode is a 3-element vector, it specifies a byte buffer in the form
{start_bsub bytestruct max_nbytes}
where bytestruct is any structure suitable for use with * move_bytes.
The buffer area starts at byte subscript start_bsub within bytestruct,
and has a maximum length of max_nbytes bytes.
... Input
----------
For input parameter data, you must set main_id to the actual number
nbytes of data bytes to be transferred before each call to sql_execute.
The data is then taken from the buffer with
move_bytes(start_bsub, bytestruct, ..., nbytes);
For all Pop types except Sql_P_string or Sql_P_binary, it is an error if
nbytes is not the exact number of bytes required for the type. For
Sql_P_string/Sql_P_binary, nbytes must be less than or equal to 254/255
unless the SQL type of the parameter is Sql_LONGVARCHAR or
Sql_LONGVARBINARY.
... Output
-----------
For output column data, each call of sql_fetch will transfer data to the
buffer with
move_bytes(..., start_bsub, bytestruct, nbytes);
and set main_id to the number nbytes of bytes transferred. (It is an
error if the buffer is not large enough, i.e. if max_nbytes is less than
nbytes.) Similarily for output parameters from sql_execute.
3.3 Procedure (Byte Stream Mode)
---------------------------------
If mode is a procedure, mode or its updater will be called inside
sql_execute or sql_fetch to transfer the data.
... Input
----------
For input parameters, you must set main_id to the total number nbytes of
data bytes to be transferred before each call to sql_execute. (If the
total is not known in advance you can set it false; however, this is
only allowable if the * sql_connect_attribute Sql_NEED_LONG_DATA_LEN is
false.)
The updater of mode will then be called inside sql_execute with nbytes
and a procedure write_p as arguments:
-> mode(nbytes, write_p)
The updater of mode must then call the procedure write_p to write chunks
of data as input, i.e.
write_p(start_bsub, bytestruct, nb)
meaning take nb bytes from bytestruct starting at byte subscript
start_bsub (where bytestruct is any structure allowed by * move_bytes).
The updater of mode may call write_p as many times as necessary to pass
all the data for the parameter.
... Output
-----------
For output column data, sql_fetch will set main_id to the total number
nbytes of data bytes (or false if this is not known in advance), and
then call the base procedure of mode with main_id and a procedure read_p
as arguments:
mode(main_id, read_p)
mode must then call the procedure read_p to receive chunks of output
data, i.e.
read_p(start_bsub, bytestruct, max_nb) -> nb
meaning read at most max_nb bytes into bytestruct starting at byte
subscript start_bsub (returning the actual number of bytes read). mode
must repeatedly call read_p to fetch all the data for the column; read_p
will return less than max_nb only at end-of-stream, and 0 when the data
is exhausted.
(Note that mode being called with main_id as argument gives mode the
option of creating a structure for the output data and assigning it to
main_id. This is potentially useful with * sql_app_result_set, where the
main_id identifiers are created internally and dereferenced
automatically after calling sql_fetch.)
The situation is identical for sql_execute output parameters, i.e. the
base procedure of mode is called to read the data. (For parameters that
are both input and output, the updater is called first to handle input,
then the base procedure to handle output.)
3.4 Special Data Values
------------------------
... NULL Values
----------------
NULL data values are represented in the Pop interface by undef records
(e.g. pop_undef).
To specify that the value of an input parameter is NULL, assign
pop_undef to the value of main_id. The mode argument is then ignored.
When an output column or parameter value is NULL, the system sets
main_id to pop_undef, and ignores mode.
... Default Parameters in SQL Procedure Calls
----------------------------------------------
To specify that an SQL procedure call should use the default value for
an input parameter, set the value of main_id to the word "default". mode
is then ignored for input.
3.5 Extended Fetch and Update
------------------------------
The Level 2 procedure sql_extended_fetch allows multiple rows to be
fetched from a result set. The number of rows to be fetched is called
the rowset size (and is determined by the * sql_statement_option
Sql_ROWSET_SIZE).
In addition, following a call to sql_extended_fetch, the Level 2
procedure sql_set_position may be called (with operation = SQL_UPDATE)
to update one or all of the fetched rows. (It may also be called to add
new rows.)
To cope with multiple rows in each column, the first DATA_BUFF item to
sql_bind_column must be a full vector main_vec rather than an identifier
main_id. The R-th element of main_vec is then used instead of main_id
for the R-th row of the rowset. The length of the vector bound to each
column must be at least as large as the rowset size (identifiers may
only be used with sql_extended_fetch if the rowset size is 1).
When main_vec is specified, the mode argument is similar, except that it
now applies to any row in the rowset instead of just one:
... Pop Value mode
-------------------
The value item for the R-th row of the column is assigned to (or for
updating, taken from) main_vec(R).
... Byte Buffer mode
---------------------
When mode is a 3-element vector {start_bsub bytestruct max_nbytes},
max_nbytes specifies the size of each row part within the column. Thus
the data area for the R-th row is assumed to start at
start_bsub + (R-1)*max_nbytes
The actual number of bytes nbytes for the R-th row is assigned to (or
for updating, taken from) main_vec(R).
... Byte Stream mode
---------------------
When mode is a procedure, the base procedure is called once for each row
R within the column, with the total number of bytes nbytes assigned to
main_vec(R). mode is called with the row number R as an additional first
argument:
mode(R, main_vec, read_p)
For updating, main_vec(R) must be set to the total number nbytes of data
bytes to be transferred for each row before the call to
sql_set_position. The updater of mode is then called once for each row
within the column with the row number R as an additional first argument:
-> mode(R, nbytes, write_p)
... Unfetched Rows
-------------------
When the actual number of rows fetched is less than the rowset size
(e.g. at the end of the result set), main_vec(R) is set to termin (and
mode ignored) for any rows not fetched. This also happens for any rows
for which an error occurred, or which were deleted (see
sql_extended_fetch).
For updating, any row for which main_vec(R) is termin will be ignored.
------------------------------
4 Connecting to a Data Source
------------------------------
sql_environment -> henv [active variable]
This active variable returns the current environment handle if
one exists, or calls SQLAllocEnv to allocate a new one
otherwise.
Once created, sql_environment holds on to the environment only
weakly via a temporary property entry, which means that a
garbage collection will reclaim it (and call SQLFreeEnv) unless
other references to it remain.
Since the environment is not required as an argument by any LIB
ODBC procedure calls, there are only two reasons for accessing
this variable explicitly, viz
# To force the environment to be created at a particular time
(e.g. on program startup -- note that SQLAllocEnv reads the
file 'odbc.ini');
# To save the environment in your own variable to prevent it
being garbaged (you should always do this if you access it).
Note that all connection and statement handles maintain a
pointer to the environment, so merely saving one of these will
also prevent the environment being garbaged.
sql_connect(conn_str, changes_p, retries, conn_mode) -> hdbc [procedure]
Establishes a connection to a data source and returns a
connection handle hdbc.
This procedure provides an interface to both SQLDriverConnect
and SQLBrowseConnect (as well as the equivalent of SQLConnect).
It performs SQLAllocConnect automatically (and accesses
* sql_environment for the environment handle).
Any of the changes_p, retries and conn_mode arguments may be
omitted; only the conn_str argument is mandatory. Unless
conn_mode is supplied and is a reference (see below), the
connection is made using SQLDriverConnect.
conn_str
This is the only required argument, and may be a single
string, or a 0- to 3-element list of strings:
[ ]
[ data_source_name ]
[ data_source_name user_name ]
[ data_source_name user_name password ]
The list elements are converted to a string suitable for
SQLDriverConnect/SQLBrowseConnect, i.e.
''
'DSN=data_source_name;'
'DSN=data_source_name; UID=user_name;'
'DSN=data_source_name; UID=user_name; PWD=password;'
If conn_str is a single string, it is interpreted as a
data_source_name (i.e. equivalent to a 1-element list),
unless it contains a semicolon: in this case, it is assumed
to be a valid connection string for SQLDriverConnect, and is
used unchanged.
changes_p
An optional procedure argument which enables any
pre-connection setting of options with * sql_connect_option.
If supplied, it is called on the newly-allocated connection
handle hdbc before making the actual connection, i.e.
changes_p(hdbc)
(Note that this is only time user code is given access to an
unconnected connection handle.)
retries
An optional integer retry count for connection attempts
(defaults to 5 if omitted). Connection attempts that fail
because of communication-link errors will be retried this
many times.
conn_mode
This optional argument is either a pair (specifying
additional arguments for SQLDriverConnect), or a reference
containing a procedure (specifying that SQLBrowseConnect
should be used instead of SQLDriverConnect).
If conn_mode is a pair, the front must contain an item
suitable for the window handle argument to SQLDriverConnect,
and the back an integer for the 'driver completion flag'
argument. The latter is one of the codes
SQL_DRIVER_NOPROMPT, SQL_DRIVER_COMPLETE, SQL_DRIVER_PROMPT
or SQL_DRIVER_COMPLETE_REQUIRED (defined in INCLUDE * ODBC),
and defaults to SQL_DRIVER_NOPROMPT if conn_mode is omitted.
To specify that SQLBrowseConnect should be used, conn_mode
must be reference containing a procedure, i.e.
consref(browse_p)
where browse_p is a procedure of the form
browse_p(result_string, sqlstate_or_false)
-> next_conn_string
SQLBrowseConnect is then called repeatedly (starting with
the initial conn_str argument) until the connection is
established. Each time it returns SQL_NEED_DATA (indicating
that more connection information is required), browse_p is
called to supply the additional information.
The two arguments passed to browse_p each time depend on
whether the previous SQLBrowseConnect call had a recoverable
error or not. If there was an error, the second argument is
the SQLSTATE string for the error, and result_string is the
associated error message obtained from SQLError. Otherwise,
the second argument is false, and result_string is the
browse result connection string.
In either case, browse_p must return an appropriate
next_conn_string as argument for the next call to
SQLBrowseConnect.
---------------------------------
5 Driver/Data Source Information
---------------------------------
sql_data_source_repeater() -> ds_rep [procedure]
Returns a repeater procedure ds_rep for data source
specifications from the 'odbc.ini' file or registry.
Each time ds_rep is called, it uses SQLDataSources to fetch the
next data source specification as a pair of strings, the data
source name and its associated driver description. That is,
ds_rep() -> pair_or_termin
where each pair has the form
conspair(data_source_name, driver_description)
ds_rep returns termin at end of stream.
sql_driver_repeater() -> dr_rep [procedure]
Returns a repeater procedure dr_rep for driver specifications
from the odbc.ini file.
Each time dr_rep is called, it uses SQLDrivers to fetch the next
driver specification as a list of strings. The first element of
the list is the driver description, and any remaining elements
are attributes in the form 'keyword=value'. That is,
dr_rep() -> list_or_termin
where each list has the form
[ driver_description attribute1 attribute2 ... ]
dr_rep returns termin at end of stream.
sql_connect_attribute(hdbc, conn_attr) -> value [procedure]
Calls SQLGetInfo to return the value of a specified attribute of
the driver/data source associated with the connection hdbc.
conn_attr specifies the attribute, and must be one of the Sql_
descriptors listed below (defined in INCLUDE * ODBC).
The table below indicates the data type of the value returned
for each attribute. Note that
# type code means one of a mutually exclusive set of integer
values defined as SQL_ constants by INCLUDE ODBC (e.g.
Sql_IDENTIFIER_CASE returns one of SQL_IC_UPPER,
SQL_IC_LOWER, SQL_IC_SENSITIVE or SQL_IC_MIXED);
# type bitmask means an integer OR'ed from a set of bitmask
values defined as SQL_ constants by INCLUDE ODBC (e.g.
Sql_ALTER_TABLE has zero or more of the bits
SQL_AT_ADD_COLUMN, SQL_AT_DROP_COLUMN set).
# attributes for which SQLGetInfo returns a Y/N string are
returned as booleans (true/false);
See SQLGetInfo for a description of each attribute.
conn_attr Type
--------- ----
Sql_ACCESSIBLE_PROCEDURES boolean
Sql_ACCESSIBLE_TABLES boolean
Sql_ACTIVE_CONNECTIONS integer
Sql_ACTIVE_STATEMENTS integer
Sql_ALTER_TABLE bitmask
Sql_BOOKMARK_PERSISTENCE bitmask
Sql_COLUMN_ALIAS boolean
Sql_CONCAT_NULL_BEHAVIOR code
Sql_CONVERT_BIGINT bitmask
Sql_CONVERT_BINARY bitmask
Sql_CONVERT_BIT bitmask
Sql_CONVERT_CHAR bitmask
Sql_CONVERT_DATE bitmask
Sql_CONVERT_DECIMAL bitmask
Sql_CONVERT_DOUBLE bitmask
Sql_CONVERT_FLOAT bitmask
Sql_CONVERT_FUNCTIONS bitmask
Sql_CONVERT_INTEGER bitmask
Sql_CONVERT_LONGVARBINARY bitmask
Sql_CONVERT_LONGVARCHAR bitmask
Sql_CONVERT_NUMERIC bitmask
Sql_CONVERT_REAL bitmask
Sql_CONVERT_SMALLINT bitmask
Sql_CONVERT_TIME bitmask
Sql_CONVERT_TIMESTAMP bitmask
Sql_CONVERT_TINYINT bitmask
Sql_CONVERT_VARBINARY bitmask
Sql_CONVERT_VARCHAR bitmask
Sql_CORRELATION_NAME code
Sql_CURSOR_COMMIT_BEHAVIOR code
Sql_CURSOR_ROLLBACK_BEHAVIOR code
Sql_DATA_SOURCE_NAME string
Sql_DATA_SOURCE_READ_ONLY boolean
Sql_DBMS_NAME string
Sql_DBMS_VER string
Sql_DEFAULT_TXN_ISOLATION code
Sql_DRIVER_NAME string
Sql_DRIVER_ODBC_VER string
Sql_DRIVER_VER string
Sql_EXPRESSIONS_IN_ORDERBY boolean
Sql_FETCH_DIRECTION bitmask
Sql_FILE_USAGE code
Sql_GETDATA_EXTENSIONS bitmask
Sql_GROUP_BY code
Sql_IDENTIFIER_CASE code
Sql_IDENTIFIER_QUOTE_CHAR string
Sql_KEYWORDS string
Sql_LIKE_ESCAPE_CLAUSE boolean
Sql_LOCK_TYPES bitmask
Sql_MAX_BINARY_LITERAL_LEN integer
Sql_MAX_CHAR_LITERAL_LEN integer
Sql_MAX_COLUMNS_IN_GROUP_BY integer
Sql_MAX_COLUMNS_IN_INDEX integer
Sql_MAX_COLUMNS_IN_ORDER_BY integer
Sql_MAX_COLUMNS_IN_SELECT integer
Sql_MAX_COLUMNS_IN_TABLE integer
Sql_MAX_COLUMN_NAME_LEN integer
Sql_MAX_CURSOR_NAME_LEN integer
Sql_MAX_INDEX_SIZE integer
Sql_MAX_OWNER_NAME_LEN integer
Sql_MAX_PROCEDURE_NAME_LEN integer
Sql_MAX_QUALIFIER_NAME_LEN integer
Sql_MAX_ROW_SIZE integer
Sql_MAX_ROW_SIZE_INCLUDES_LONG boolean
Sql_MAX_STATEMENT_LEN integer
Sql_MAX_TABLES_IN_SELECT integer
Sql_MAX_TABLE_NAME_LEN integer
Sql_MAX_USER_NAME_LEN integer
Sql_MULTIPLE_ACTIVE_TXN boolean
Sql_MULT_RESULT_SETS boolean
Sql_NEED_LONG_DATA_LEN boolean
Sql_NON_NULLABLE_COLUMNS boolean
Sql_NULL_COLLATION code
Sql_NUMERIC_FUNCTIONS bitmask
Sql_ODBC_API_CONFORMANCE code
Sql_ODBC_SAG_CLI_CONFORMANCE code
Sql_ODBC_SQL_CONFORMANCE code
Sql_ODBC_SQL_OPT_IEF boolean
Sql_ODBC_VER string
Sql_OJ_CAPABILITIES bitmask
Sql_ORDER_BY_COLUMNS_IN_SELECT boolean
Sql_OUTER_JOINS boolean
Sql_OWNER_TERM string
Sql_OWNER_USAGE bitmask
Sql_POSITIONED_STATEMENTS bitmask
Sql_POS_OPERATIONS bitmask
Sql_PROCEDURES boolean
Sql_PROCEDURE_TERM string
Sql_QUALIFIER_LOCATION code
Sql_QUALIFIER_NAME_SEPARATOR string
Sql_QUALIFIER_TERM string
Sql_QUALIFIER_USAGE bitmask
Sql_QUOTED_IDENTIFIER_CASE code
Sql_ROW_UPDATES boolean
Sql_SCROLL_CONCURRENCY bitmask
Sql_SCROLL_OPTIONS bitmask
Sql_SEARCH_PATTERN_ESCAPE string
Sql_SERVER_NAME string
Sql_SPECIAL_CHARACTERS string
Sql_STATIC_SENSITIVITY bitmask
Sql_STRING_FUNCTIONS bitmask
Sql_SUBQUERIES bitmask
Sql_SYSTEM_FUNCTIONS bitmask
Sql_TABLE_TERM string
Sql_TIMEDATE_ADD_INTERVALS bitmask
Sql_TIMEDATE_DIFF_INTERVALS bitmask
Sql_TIMEDATE_FUNCTIONS bitmask
Sql_TXN_CAPABLE code
Sql_TXN_ISOLATION_OPTION bitmask
Sql_UNION bitmask
Sql_USER_NAME string
sql_connect_functions(hdbc) -> bitmask [procedure]
sql_connect_functions(hdbc, func_number) -> bool
Calls SQLGetFunctions to return information on which ODBC
functions are supported by the driver on the connection hdbc.
Each function is identified by a number from 1 to 100; constants
for these numbers have names of the form SQL_API_functionname.
Note that INCLUDE * ODBC defines these names only for Extension
Level 2 functions, since LIB ODBC assumes Level 1 functionality
is always present.
In the first form, sql_connect_functions calls SQLGetFunctions
to get information about all functions, and returns this as a
biginteger bitmask in which bit N is set if the driver supports
function number N. bitmask can therefore be used with
testbit(bitmask, func_number)
to test for an individual func_number. (Note that the bitmask
result is cached inside hdbc so that subsequent calls to
sql_connect_functions do not have to reconstruct it.)
In the second form, sql_connect_functions returns a boolean bool
pertaining to the individual function given by func_number.
sql_select_types(hstmt) [procedure]
sql_select_types(hstmt, sql_type)
Calls SQLGetTypeInfo to create a result set describing the data
types supported by a data source. hstmt is a statement handle
for the result set.
If sql_type is supplied, it must be a LIB ODBC SQL type
descriptor (see SQL Data Types above); in this case, the result
set has rows only for those data source types which correspond
to sql_type. If sql_type is omitted, all possible data types are
enumerated.
See SQLGetTypeInfo for details of the columns in each row of the
result set.
-----------------
6 Driver Options
-----------------
sql_connect_option(hdbc, conn_option) -> value [procedure]
value -> sql_connect_option(hdbc, conn_option)
Calls SQLGetConnectOption/SQLSetConnectOption to access or
update the value of a specified option setting for the
connection hdbc.
conn_option specifies the option, and must be one of the Sql_
descriptors listed below (and defined in INCLUDE * ODBC). For
the updater only, conn_option may also be any valid option to
sql_statement_option (i.e. to set a statement option for all
subsequently-created statements on hdbc).
The table below indicates the data type of the value returned
for each option. Note that type code means one of a mutually
exclusive set of integer values defined as SQL_ constants by
INCLUDE ODBC (e.g. Sql_ACCESS_MODE returns one of
SQL_MODE_READ_WRITE or SQL_MODE_READ_ONLY).
Certain options also have a default value defined for them:
these are shown in the table. For any option whose value has not
previously been set, sql_connect_option will return the default
if the option has one, or pop_undef otherwise. In addition, an
option with a default value may be set to that default by
assigning the word "default" to the updater.
See SQLSetConnectOption for a description of each option.
conn_option Type Default
----------- ---- -------
Sql_ACCESS_MODE code SQL_MODE_READ_WRITE
Sql_AUTOCOMMIT boolean true
Sql_CURRENT_QUALIFIER string
Sql_LOGIN_TIMEOUT integer 15
Sql_ODBC_CURSORS code SQL_CUR_USE_DRIVER
Sql_OPT_TRACE boolean false
Sql_OPT_TRACEFILE string
Sql_PACKET_SIZE integer
Sql_TRANSLATE_DLL string
Sql_TRANSLATE_OPTION integer
Sql_TXN_ISOLATION code
sql_statement_option(hstmt, stmt_option) -> value [procedure]
value -> sql_statement_option(hstmt, stmt_option)
Calls SQLGetStmtOption/SQLSetStmtOption to access or update the
value of a specified option setting for the statement hstmt.
stmt_option specifies the option, and must be one of the Sql_
descriptors listed below (and defined in INCLUDE * ODBC).
The table below indicates the data type of the value returned
for each option. Note that type code means one of a mutually
exclusive set of integer values defined as SQL_ constants by
INCLUDE ODBC (e.g. Sql_ACCESS_MODE returns one of
SQL_MODE_READ_WRITE or SQL_MODE_READ_ONLY).
Certain options also have a default value defined for them:
these are shown in the table. For any option whose value has not
previously been set, sql_statement_option will return the
default if the option has one, or pop_undef otherwise. In
addition, an option with a default value may be set to that
default by assigning the word "default" to the updater.
Note that the Sql_ASYNC_ENABLE option is special insofar as its
value is false or a procedure. See Asynchronous Statement
Processing below.
See SQLSetStmtOption for a description of each option.
stmt_option Type Default
----------- ---- -------
Sql_ASYNC_ENABLE boolean false
Sql_CONCURRENCY code SQL_CONCUR_READ_ONLY
Sql_CURSOR_TYPE code SQL_CURSOR_FORWARD_ONLY
Sql_KEYSET_SIZE integer 0
Sql_MAX_LENGTH integer 0
Sql_MAX_ROWS integer 0
Sql_NOSCAN boolean false
Sql_QUERY_TIMEOUT integer 0
Sql_RETRIEVE_DATA boolean true
Sql_ROWSET_SIZE integer 1
Sql_SIMULATE_CURSOR code
Sql_USE_BOOKMARKS boolean false
The following options are read-only (i.e. may be accessed but
not set, see SQLGetStmtOption):
Sql_GET_BOOKMARK integer
Sql_ROW_NUMBER integer
There is also the following option, which is special to LIB ODBC
(and is used by * sql_extended_fetch when Sql_ROWSET_SIZE is
greater than 1):
Sql_LONG_DATA_MAX integer 2047
-------------------------
7 Preparing SQL Requests
-------------------------
sql_alloc_statement(hdbc) -> hstmt [procedure]
Calls SQLAllocStmt to allocate a new statement handle hstmt on
the connection hdbc.
sql_prepare(hstmt, sql_string) [procedure]
Calls SQLPrepare to prepare the SQL string sql_string for
execution on the statement hstmt. All parameters and columns on
hstmt are unbound first.
sql_num_parameters(hstmt) -> num_parameters [procedure]
(Extension Level 2) Returns the number of parameters in the
prepared statement hstmt (by calling SQLNumParams).
sql_describe_parameter(hstmt, N) -> (sql_type, nullable) [procedure]
sql_describe_parameter(hstmt, N, unsigned)
-> (sql_type, nullable)
(Extension Level 2) Returns the LIB ODBC SQL type of the N-th
parameter in the prepared statement hstmt (by calling
SQLDescribeParam).
The nullable result is one of the values SQL_NO_NULLS,
SQL_NULLABLE or SQL_NULLABLE_UNKNOWN (defined in
INCLUDE * ODBC).
Because SQLDescribeParam does not provide any indication of
whether whether an integer type is signed or unsigned, the
optional boolean argument unsigned may be supplied: this is
passed as the last argument to * sql_cons_sql_type when the
sql_type result is constructed (and defaults to false).
sql_bind_parameter(hstmt, N, DATA_BUFF, sql_type) [procedure]
sql_bind_parameter(hstmt, N, DATA_BUFF, sql_type, pop_type)
sql_bind_parameter(hstmt, N, DATA_BUFF, sql_type, pop_type,
param_type)
Binds a buffer for the N-th parameter marker in a statement
hstmt (where N >= 1). This procedure calls SQLBindParameter.
DATA_BUFF specifies the buffer mechanism, and represents either
one or two arguments. These are described fully in the section
Data Input/Output Modes above.
sql_type specifies the LIB ODBC SQL type of the parameter, and
must be one of the Sql_ types listed under SQL Data Types above.
pop_type is an optional Pop data type for the parameter; if
supplied, it must be one of the Sql_P_ types listed under Pop
Data Types above. If pop_type is omitted, it defaults to the
default Pop type for sql_type (see SQL Data Types).
param_type is an optional parameter type, and must be one of the
constants SQL_PARAM_INPUT, SQL_PARAM_INPUT_OUTPUT or
SQL_PARAM_OUTPUT defined in INCLUDE * ODBC. If omitted, it
defaults to SQL_PARAM_INPUT. (Note that if param_type is
supplied, pop_type is mandatory; however, in this case pop_type
may be false to mean use the default Pop type for sql_type.)
The form
sql_bind_parameter(hstmt, "*", false);
may also be used to unbind all parameters on hstmt (there is no
mechanism for unbinding a single parameter).
sql_cursor_name(hstmt) -> string_or_false [procedure]
string_or_false -> sql_cursor_name(hstmt)
Returns or updates the name of the cursor associated with the
statement hstmt.
The base procedure call SQLGetCursorName to access the cursor
name. false is returned if there is no open cursor on hstmt (and
the updater has not been called to set an explicit name).
If the updater is given a string, it calls SQLSetCursorName to
associate a cursor name with hstmt (this may only be done before
the cursor is opened, i.e. before the statement is executed).
If the updater is given false, it calls SQLFreeStmt with the
SQL_CLOSE option to close the cursor. (However, note that if an
explicit cursor name has been set, this remains associated with
hstmt even though there is no open cursor; hence the base
procedure will continue to return that name rather than false.)
----------------------
8 Submitting Requests
----------------------
sql_execute(hstmt) [procedure]
sql_execute(hstmt, sql_string)
In the first form, calls SQLExecute to execute an SQL statement
hstmt already prepared with * sql_prepare. In the second form,
calls SQLExecDirect to execute the SQL statement sql_string.
In both cases, the current values of any parameters bound with
* sql_bind_parameter are used for the corresponding parameter
markers in the statement.
sql_native_sql(hdbc, sql_string) -> native_sql_string [procedure]
(Extension Level 2) Given a connection hdbc, returns the
driver's translation of the SQL statement string sql_string.
------------------------------------------
9 Retrieving Results & Result Information
------------------------------------------
sql_row_count(hstmt) -> row_count [procedure]
Calls SQLRowCount to return the number of rows affected by an
UPDATE, INSERT or DELETE statement previously executed on hstmt
(or alternatively, by an SQL_UPDATE, SQL_ADD, or SQL_DELETE
operation with * sql_set_position).
sql_num_result_columns(hstmt) -> num_columns [procedure]
Calls SQLNumResultCols to return the number of columns in the
result set associated with the (prepared or executed) statement
hstmt.
0 is returned if hstmt is a statement that did not create a
result set.
sql_describe_column(hstmt, N) -> (name, sql_type, nullable) [procedure]
Returns the column name and LIB ODBC SQL type of the N-th column
in the result set on the statement hstmt (by calling
SQLDescribeCol).
The nullable result is one of the values SQL_NO_NULLS,
SQL_NULLABLE or SQL_NULLABLE_UNKNOWN (defined in
INCLUDE * ODBC).
For integer types, this procedure calls * sql_column_attribute
to determine the Sql_COLUMN_UNSIGNED attribute of the column,
which is then included in the sql_type result.
sql_column_attribute(hstmt, N, col_attr) -> value [procedure]
Calls SQLColAttributes to return the value of a specified
attribute of the N-th column in a result set.
col_attr specifies the attribute, and must be one of the Sql_
descriptors listed below (and defined in INCLUDE * ODBC).
The table below indicates the data type of the value returned
for each attribute. Note that type code means one of a mutually
exclusive set of integer values defined as SQL_ constants by
INCLUDE ODBC (e.g. Sql_COLUMN_NULLABLE returns one of
SQL_NO_NULLS, SQL_NULLABLE or SQL_NULLABLE_UNKNOWN).
See SQLColAttributes for a description of each attribute.
col_attr Type
-------- ----
Sql_COLUMN_AUTO_INCREMENT boolean
Sql_COLUMN_CASE_SENSITIVE boolean
Sql_COLUMN_COUNT integer
Sql_COLUMN_DISPLAY_SIZE integer
Sql_COLUMN_LABEL string
Sql_COLUMN_LENGTH integer
Sql_COLUMN_MONEY boolean
Sql_COLUMN_NAME string
Sql_COLUMN_NULLABLE code
Sql_COLUMN_OWNER_NAME string
Sql_COLUMN_PRECISION integer
Sql_COLUMN_QUALIFIER_NAME string
Sql_COLUMN_SCALE integer
Sql_COLUMN_SEARCHABLE code
Sql_COLUMN_TABLE_NAME string
Sql_COLUMN_TYPE integer
Sql_COLUMN_TYPE_NAME string
Sql_COLUMN_UNSIGNED boolean
Sql_COLUMN_UPDATABLE code
sql_bind_column(hstmt, N, DATA_BUFF) [procedure]
sql_bind_column(hstmt, N, DATA_BUFF, pop_type)
Binds a buffer for the N-th column of the result set on the
statement hstmt (where N >= 0).
DATA_BUFF specifies the buffer mechanism, and represents either
one or two arguments. These are described fully in the section
Data Input/Output Modes above.
pop_type is an optional Pop data type for the column; if
supplied, it must be one of the Sql_P_ types listed under Pop
Data Types above. If pop_type is omitted, it defaults to the
default Pop type for the SQL type of the column (see SQL Data
Types). For N = 0 (i.e. binding the bookmark column), pop_type
defaults to Sql_P_bookmark.
The forms
sql_bind_column(hstmt, N, false);
sql_bind_column(hstmt, "*", false);
can also be used to unbind either a single column or all columns
on hstmt.
(N.B. In general, sql_bind_column does not actually call
SQLBindCol -- this is because sql_fetch uses SQLGetData to fetch
the data for all columns. Hence any errors that might be
expected from SQLBindCol will instead occur during sql_fetch.
The same is true for * sql_extended_fetch with a rowset size of
1; however, sql_extended_fetch with a rowset size greater than 1
does call SQLBindCol.)
sql_fetch(hstmt) -> data_found [procedure]
Calls SQLFetch to fetch the next row of data from the result set
on the statement hstmt.
If a row was fetched, any columns bound with * sql_bind_column
have data transferred to their buffers (by calls to SQLGetData),
and true is returned.
false is returned when there are no rows left.
sql_app_result_set(hstmt, col_select, app_p) [procedure]
sql_app_result_set(hstmt, col_select, init_p, app_p)
A convenience procedure that enables processing of a result set
without explicit use of sql_bind_column and sql_fetch. The
procedure app_p is applied to every row of the result set on the
statement hstmt.
The col_select argument selects the column numbers to be
processed, which can range between 1 and
sql_num_result_columns(hstmt) inclusive. col_select is a list of
column specifiers,
[ col_spec1 col_spec2 ... col_specM ]
where each col_spec is either a col_num_spec or a 2- or
3-element full vector whose first element is a col_num_spec:
{ col_num_spec 1_or_2_bind_args }
A col_num_spec is either
# a single column number;
# a 2-element list [first_col last_col], meaning columns
first_col to last_col inclusive;
# the word "*", meaning all remaining columns.
(Note that column numbers outside the range 1 to
sql_num_result_columns(hstmt) are ignored.)
Every column selected is bound with sql_bind_column. In each
case, the main_id identifier for the first DATA_BUFF item to
sql_bind_column is generated automatically; if the col_spec that
selected a column is a vector, the remaining one or two elements
of col_spec are passed as additional arguments to the
sql_bind_column call for that column. These elements thus
represent the mode part of DATA_BUFF and/or the pop_type
arguments to sql_bind_column.
For example, the col_select list
[ 1 [3 5] {[7 10] ^Sql_P_int} {* ^Sql_P_string} ]
selects columns 1, 3-5, 7-10 with pop_type Sql_P_int, and 11
onwards with pop_type Sql_P_string. (With all columns returning
data in Pop value mode.)
sql_fetch is then called to fetch each row of the result set.
For each row, app_p is applied to the set of values for the
selected columns, together with the number of columns selected.
That is, if column numbers c1, ..., cN are selected, then app_p
is called as
app_p(c1_val, c2_val, ..., cN_val, N);
where each cI_val is the idval of the main_id identifier for
that column.
init_p Argument
The optional procedure argument init_p allows some initial
processing to be done for each selected column. If supplied,
then before fetching any rows, init_p is called once for each
column c1, ..., cN, with hstmt and the column number cI as
arguments:
init_p(hstmt, cI) -> cI_results
Any results returned by init_p for column cI will be saved and
added as additional (constant) arguments following the cI_val
argument to every call of app_p. That is, app_p will be called
as
app_p(c1_val, c1_results, c2_val, c2_results, ...,
cN_val, cN_results, nargs);
where nargs is the total number of arguments.
In addition, init_p is called an extra (N+1)-th time with false
for the column number (which call must not return any results).
This allows any final processing to take place before fetching
the row data.
sql_extended_fetch(hstmt, fetch_type, row_num, [procedure]
row_status_vec) -> nrows_or_false
(Extension Level 2) Calls SQLExtendedFetch to fetch specified
row(s) from the result set on the statement hstmt.
The number of rows to be fetched is called the rowset size, and
is determined by the * sql_statement_option Sql_ROWSET_SIZE.
Binding Buffers
For each row fetched, any columns bound with * sql_bind_column
have data transferred to their buffers. If the rowset size is
greater than 1, the DATA_BUFF arguments to sql_bind_column must
have supplied full vectors of appropriate length rather than
identifiers -- see Extended Fetch and Update above.
With a rowset size of 1, sql_extended_fetch uses the same
mechanism as sql_fetch for fetching data (i.e. SQLGetData).
However, with a rowset size greater than 1, this mechanism is
problematical and so (currently), the first call of
sql_extended_fetch on an hstmt will cause all columns to become
bound with SQLBindCol instead. The latter necessitates
allocating an internal buffer of sufficient size to hold all the
data for each column, and forces sql_extended_fetch to impose a
limit on columns with LONG data types (i.e. Sql_LONGVARCHAR and
Sql_LONGVARBINARY). This limit is specified by the special
* sql_statement_option Sql_LONG_DATA_MAX, and represents the
maximum number of bytes that should be allowed for a LONG column
of data in a single row. Sql_LONG_DATA_MAX defaults to 2047
bytes.
(Note: The row-wise binding facility of SQLExtendedFetch is not
supported by sql_extended_fetch.)
fetch_type and row_num Arguments
The position of the rowset fetched within the result set is
determined by the fetch_type argument, either alone, or in
conjunction with the current cursor position or the row_num
argument, as shown below. (After a rowset is fetched, the cursor
is positioned on the first row of the rowset.)
fetch_type Action
---------- ------
SQL_FETCH_NEXT Fetches the next rowset. If the
cursor is positioned before the
start of the result set (as
initially), this is the same as
SQL_FETCH_FIRST.
SQL_FETCH_PRIOR Fetches the previous rowset. If the
cursor is positioned after the end
of the result set, this is the same
as SQL_FETCH_LAST.
SQL_FETCH_RELATIVE Fetches the rowset row_num rows from
the start of the current rowset; if
row_num is 0, the current rowset is
re-fetched. If the cursor is
positioned before the start of the
result set and row_num is greater
than 0, or if the cursor is
positioned after the end of the
result set and row_num is less than
0, this is the same as
SQL_FETCH_ABSOLUTE.
SQL_FETCH_FIRST Fetches the first rowset in the
result set.
SQL_FETCH_LAST Fetches the last complete rowset in
the result set.
SQL_FETCH_ABSOLUTE If row_num is greater than 0,
fetches the rowset starting at row
row_num; if row_num equals 0, false
is returned (and the cursor is
positioned before the start of the
result set); if row_num is less than
0, fetches the rowset starting at
row L+row_num+1, where L is the last
row in the result set.
SQL_FETCH_BOOKMARK Fetches the rowset starting with the
row whose bookmark is row_num.
The row_num argument is ignored for those values of fetch_type
that do not require it, and may be omitted in these cases;
fetch_type itself may be omitted (together with row_num) when
the fetch type required is SQL_FETCH_NEXT.
row_status_vec Argument
The row_status_vec argument is optional; if supplied, it must be
a full vector of length greater than or equal to the rowset
size. The elements of this vector are then set to one of the
following integer status values for each row fetched:
SQL_ROW_SUCCESS
SQL_ROW_DELETED
SQL_ROW_UPDATED
SQL_ROW_ADDED
SQL_ROW_ERROR
Any remaining elements of row_status_vec for unfetched rows (up
to the rowset size) are set to SQL_ROW_NOROW. (As mentioned in
Extended Fetch and Update above, rows with status SQL_ROW_NOROW,
SQL_ROW_DELETED or SQL_ROW_ERROR have their main_id/main_vec
column buffer entries set to termin.)
Note that row_status_vec is saved inside hstmt so that its
elements may be modified by a subsequent call to
* sql_set_position.
Result
sql_extended_fetch returns the actual number of rows fetched, or
false at end-of-stream in either direction.
sql_set_position(hstmt, row_num, operation, lock) [procedure]
(Extension Level 2) Following a call to * sql_extended_fetch to
fetch a rowset from the statement hstmt, sql_set_position sets
the cursor position within the rowset, and allows an application
to refresh, update, delete or add data to the rowset. (This
procedure calls SQLSetPos.)
The row_num argument specifies the row number within the rowset
on which to perform the operation, or is 0 if the operation
should be performed on all rows in the rowset (0 is not valid
for operation = SQL_POSITION). Except for operation = SQL_ADD,
row_num must be less than or equal to the rowset size.
The operation argument specifies the operation to be performed,
as follows:
operation Action
--------- ------
SQL_POSITION Sets the cursor on row number row_num.
SQL_REFRESH If row_num is nonzero, sets the cursor on
row number row_num, and re-fetches the data
for that row; if row_num is 0, re-fetches
the data for all rows in the rowset (and
leaves the cursor position unchanged).
SQL_UPDATE If row_num is nonzero, sets the cursor on
row number row_num, and then updates the row
from the column buffers; if row_num is 0,
updates all rows in the rowset (and leaves
the cursor position unchanged). Note that
columns whose main_id/main_vec buffer
entries for the updated row(s) are termin
will be ignored (see Extended Fetch and
Update above).
SQL_DELETE If row_num is nonzero, sets the cursor on
row number row_num, and then deletes the
underlying row; if row_num is 0, deletes all
rows in the rowset (and leaves the cursor
position unchanged).
SQL_ADD If row_num is nonzero, adds a new row of
data to the data source, using the column
buffer entries for row_num (which may be
greater than the rowset size, providing all
main_vec buffers have a corresponding
element). If row_num is 0, adds rowset-size
new rows. Unbound columns (or columns
containing termin for a row) will use
default or NULL values in the new row(s).
The operation argument may be omitted provided the lock argument
is also; in this case, operation defaults to SQL_POSITION (and
lock to SQL_LOCK_NO_CHANGE).
Note that if a row_status_vec was supplied to the preceding call
of sql_extended_fetch, all operations except SQL_POSITION may
modify the elements of row_status_vec to reflect the new status
of row(s) affected by the operation.
The lock argument is optional; if supplied, it must be one of
SQL_LOCK_NO_CHANGE (the default), SQL_LOCK_EXCLUSIVE or
SQL_LOCK_UNLOCK. See SQLSetPos for more details.
----------------------------------------
10 Data Source System Table Information
----------------------------------------
sql_select_columns(hstmt, tab_qual, tab_owner, tab_name, [procedure]
col_name)
Calls SQLColumns to create a result set on the statement hstmt
describing the columns in specified tables on the data source.
tab_qual, tab_owner, tab_name and col_name are respectively the
table qualifier name, table owner name, table name, and column
name arguments to SQLColumns, and may each be a string or false
(the latter meaning pass a NULL pointer for the argument).
See SQLColumns for more details.
sql_select_special_columns(hstmt, col_type, tab_qual, [procedure]
tab_owner, tab_name, scope, nullable)
Calls SQLSpecialColumns to create a result set on the statement
hstmt describing special columns in specified tables on the data
source.
col_type must be either SQL_BEST_ROWID or SQL_ROWVER.
tab_qual, tab_owner and tab_name are respectively the table
qualifier name, table owner name, and table name arguments to
SQLSpecialColumns, and may each be a string or false (the latter
meaning pass a NULL pointer for the argument).
scope is one of SQL_SCOPE_CURROW, SQL_SCOPE_TRANSACTION or
SQL_SCOPE_SESSION; nullable is either SQL_NO_NULLS or
SQL_NULLABLE.
See SQLSpecialColumns for more details.
sql_select_statistics(hstmt, tab_qual, tab_owner, tab_name, [procedure]
unique, accuracy)
Calls SQLStatistics to create a result set on the statement
hstmt describing statistics and indexes for a single table on
the data source.
tab_qual, tab_owner, and tab_name are respectively the table
qualifier name, table owner name, and table name arguments to
SQLStatistics. tab_qual and tab_owner may be a string or false
(the latter meaning pass a NULL pointer for the argument);
tab_name must be string.
unique is either SQL_INDEX_UNIQUE or SQL_INDEX_ALL; accuracy is
either SQL_ENSURE or SQL_QUICK.
See SQLStatistics for more details.
sql_select_tables(hstmt, tab_qual, tab_owner, tab_name, [procedure]
tab_type)
Calls SQLTables to create a result set on the statement hstmt
listing the tables available on the data source.
tab_qual, tab_owner, tab_name and tab_type are respectively the
table qualifier name, table owner name, table name, and table
type arguments to SQLTables, and may each be a string or false
(the latter meaning pass a NULL pointer for the argument).
See SQLTables for more details.
sql_select_column_privileges(hstmt, tab_qual, tab_owner, [procedure]
tab_name, col_name)
(Extension Level 2) Calls SQLColumnPrivileges to create a result
set on the statement hstmt describing the associated privileges
of columns in specified tables on the data source.
tab_qual, tab_owner, tab_name and col_name are respectively the
table qualifier name, table owner name, table name, and column
name arguments to SQLColumnPrivileges, and may each be a string
or false (the latter meaning pass a NULL pointer for the
argument).
See SQLColumnPrivileges for more details.
sql_select_table_privileges(hstmt, tab_qual, tab_owner, [procedure]
tab_name)
(Extension Level 2) Calls SQLTablePrivileges to create a result
set on the statement hstmt describing privilege information
about tables on the data source.
tab_qual, tab_owner and tab_name are respectively the table
qualifier name, table owner name and table name arguments to
SQLTablePrivileges, and may each be a string or false (the
latter meaning pass a NULL pointer for the argument).
See SQLTablePrivileges for more details.
sql_select_primary_keys(hstmt, tab_qual, tab_owner, [procedure]
tab_name)
(Extension Level 2) Calls SQLPrimaryKeys to create a result set
on the statement hstmt listing the column names that comprise
the primary key for a specified table.
tab_qual, tab_owner, and tab_name are respectively the table
qualifier name, table owner name, and table name arguments to
SQLPrimaryKeys . tab_qual and tab_owner may be a string or false
(the latter meaning pass a NULL pointer for the argument);
tab_name must be string.
See SQLPrimaryKeys for more details.
sql_select_foreign_keys(hstmt, [procedure]
pktab_qual, pktab_owner, pktab_name,
fktab_qual, fktab_owner, fktab_name)
(Extension Level 2) Calls SQLForeignKeys to create a result set
on the statement hstmt listing foreign keys in a specified
table.
pktab_qual, pktab_owner and pktab_name are respectively the
primary key table qualifier name, table owner name and table
name arguments to SQLForeignKeys; fktab_qual, fktab_owner and
fktab_name are respectively the foreign key table qualifier
name, table owner name and table name arguments to
SQLForeignKeys.
All these arguments may be a string or false (the latter meaning
pass a NULL pointer for the argument), except that either
pktab_name or fktab_name (or both) must be a string.
See SQLForeignKeys for more details.
----------------------------------------
11 Terminating Statements & Connections
----------------------------------------
sql_transact(hdbc) [procedure]
sql_transact(hdbc, commit)
Calls SQLTransact to commit or rollback all active operations on
all statements associated with the connection hdbc.
The optional boolean argument commit is true for commit, false
for rollback, and defaults to true if omitted.
The form
sql_transact(false, commit);
may also be used to perform a commit/rollback operation on all
current connections.
Note that the * sql_connect_option SQL_AUTOCOMMIT is true by
default on any connection, and causes all transactions to be
committed automatically. See SQLTransact for further details.
sql_free_statement(hstmt) [procedure]
Calls SQLFreeStmt (with operation SQL_DROP) to free the
statement hstmt and release all associated resources. (This
procedure is the * sys_process_destroy_action of every hstmt.)
sql_disconnect(hdbc) [procedure]
Calls SQLDisconnect to close the connection hdbc and release all
associated resources. (This procedure is the
* sys_process_destroy_action of every hdbc.)
-------------------------------------
12 Asynchronous Statement Processing
-------------------------------------
Providing a given driver supports it, the Sql_ASYNC_ENABLE option to
* sql_statement_option enables processing on a statement to happen
asynchronously.
In this mode, calls to certain ODBC C functions (such as SQLExecute and
SQLFetch) initiate an operation on a statement and then return the
status code SQL_STILL_EXECUTING. The function must then be called
repeatedly to determine whether processing has finished (i.e. until
something other than SQL_STILL_EXECUTING is returned).
The corresponding LIB ODBC procedures handle this by repeatedly calling
the underlying C function in a loop, with a 'wait' procedure being
called each time the function returns SQL_STILL_EXECUTING.
The wait procedure used is the value of the Sql_ASYNC_ENABLE option for
the hstmt. If true is assigned to the option value, the procedure
defaults to syssleep(%1%), but any suitable procedure can be used.
In particular, either an individual LIB ODBC procedure or a whole
application can be run as a process (see REF * PROCESS), with a wait
procedure that suspends the process. A timer can then resume the process
at appropriate intervals, or (more efficiently), use sql_statement_busy
to test if the statement has finished executing before resuming the
process.
sql_statement_busy(hstmt) -> busy [procedure]
false -> sql_statement_busy(hstmt)
The base procedure returns true if the statement hstmt is busy,
i.e. has an asynchronous operation still in progress. false is
returned otherwise.
The updater is an interface to SQLCancel, and allows an
asynchronous operation on hstmt to be cancelled by assigning
false (any other value is ignored).
The LIB ODBC procedures that can call a wait procedure if asynchronous
processing has been enabled on their hstmt argument are listed below.
* sql_app_result_set* sql_column_attribute* sql_describe_column* sql_describe_parameter* sql_execute* sql_extended_fetch* sql_fetch* sql_num_parameters* sql_num_result_columns* sql_prepare
* sql_select_column_privileges
* sql_select_columns* sql_select_foreign_keys* sql_select_primary_keys* sql_select_special_columns* sql_select_statistics* sql_select_table_privileges* sql_select_tables* sql_select_types* sql_set_position
------------
13 Examples
------------
The following two examples are Pop-11 translations of the the C examples
given in Chapter 10 of ODBC SDK Programmer's Reference.
13.1 Static SQL
----------------
include odbc.ph;
define example1(conn_str);
lvars ID, Name, hdbc, hstmt;
;;; Connect to conn_str (which may be a string in DriverConnect
;;; format, or a list [^server ^user ^password] etc).
sql_connect(conn_str) -> hdbc;
;;; allocate a statement handle
sql_alloc_statement(hdbc) -> hstmt;
;;; EXEC SQL CREATE TABLE NAMEID (ID integer, NAME varchar(50));
;;; Execute the SQL statement
sql_execute(hstmt,
'CREATE TABLE NAMEID (ID INTEGER, NAME VARCHAR(50))');
;;; EXEC SQL COMMIT WORK;
;;; Commit the table creation.
;;; (Note that the default transaction mode is auto-commit
;;; and sql_transact has no effect.)
sql_transact(hdbc);
;;; EXEC SQL INSERT INTO NAMEID VALUES (:id, :name);
;;; Show the use of the sql_prepare/sql_execute method:
;;; Prepare the insertion and bind parameters;
;;; Assign parameter values;
sql_prepare(hstmt, 'INSERT INTO NAMEID VALUES (?, ?)');
sql_bind_parameter(hstmt, 1, ident ID, Sql_INTEGER);
sql_bind_parameter(hstmt, 2, ident Name, Sql_VARCHAR(50));
;;; Execute the insertions.
(500, 'Babbage') -> (ID, Name);
sql_execute(hstmt);
(600, 'Turing') -> (ID, Name);
sql_execute(hstmt);
;;; EXEC SQL COMMIT WORK;
;;; Commit the insertions
sql_transact(hdbc);
;;; EXEC SQL DECLARE c1 CURSOR FOR SELECT ID, NAME FROM NAMEID;
;;; EXEC SQL OPEN c1;
;;; Show the use of the sql_execute direct method.
;;; Execute the selection.
;;; (Note that the application does not declare a cursor name.)
sql_execute(hstmt, 'SELECT ID, NAME FROM NAMEID');
;;; EXEC SQL FETCH c1 INTO :id, :name;
;;; Bind the columns of the result set with sql_bind_column.
;;; Fetch and print all rows.
sql_bind_column(hstmt, 1, ident ID);
sql_bind_column(hstmt, 2, ident Name);
while sql_fetch(hstmt) do
[ID ^ID Name ^Name] ==>
endwhile;
sql_transact(hdbc);
sql_disconnect(hdbc);
enddefine;
13.2 Ad Hoc Query
------------------
include odbc.ph;
define example2(conn_str, sql_string);
lvars nresultcols, rowcount, N, id, name, dsize, col_list, col,
hdbc, hstmt;
sql_connect(conn_str) -> hdbc;
sql_alloc_statement(hdbc) -> hstmt;
;;; Execute the given SQL statement
sql_execute(hstmt, sql_string);
;;; See what kind of statement it was. If there are no result
;;; columns, the statement is not a SELECT. If the number of
;;; affected rows is greater than 0, the statement was probably an
;;; UPDATE, INSERT or DELETE, so print the number of affected rows.
;;; If the number of affected rows is 0, print that the operation
;;; was successful and commit it.
sql_num_result_columns(hstmt) -> nresultcols;
if nresultcols == 0 then
sql_row_count(hstmt) -> rowcount;
if rowcount == 0 then
printf('%p rows affected.\n', [^rowcount])
else
printf('Operation successful.\n')
endif;
;;; Otherwise, use sql_column_attribute to get and display the
;;; column names of the result set, and also to find the display
;;; size needed for each column. Then bind each column (specifying
;;; that all data should be converted to string format), and make a
;;; list of columns in which each element contains the id and the
;;; display size for that column. Finally, fetch and print each row.
else
[% for N to nresultcols do
sql_column_attribute(hstmt, N, Sql_COLUMN_NAME) -> name;
sql_column_attribute(hstmt, N, Sql_COLUMN_DISPLAY_SIZE)
-> dsize;
max(dsize, datalength(name)) + 1 -> dsize;
pr_field(name, dsize, false, `\s`);
consident(0, 0, "lex") -> id;
sql_bind_column(hstmt, N, id, Sql_P_string);
[^id ^dsize]
endfor
%] -> col_list;
cucharout(`\n`);
while sql_fetch(hstmt) do
for col in col_list do
dl(col) -> (id, dsize);
pr_field(idval(id), dsize, false, `\s`);
endfor;
cucharout(`\n`)
endwhile
endif;
sql_transact(hdbc);
sql_disconnect(hdbc)
enddefine;
... Using sql_app_result_set
-----------------------------
Another version of example2, but using * sql_app_result_set.
define example2(conn_str, sql_string);
lvars nresultcols, rowcount, hdbc, hstmt;
sql_connect(conn_str) -> hdbc;
sql_alloc_statement(hdbc) -> hstmt;
sql_execute(hstmt, sql_string);
sql_num_result_columns(hstmt) -> nresultcols;
if nresultcols == 0 then
sql_row_count(hstmt) -> rowcount;
if rowcount == 0 then
printf('%p rows affected.\n', [^rowcount])
else
printf('Operation successful.\n')
endif;
else
define init_col(hstmt, N);
lvars name, dsize;
if N then
sql_column_attribute(hstmt, N, Sql_COLUMN_NAME) -> name;
sql_column_attribute(hstmt, N, Sql_COLUMN_DISPLAY_SIZE)
-> dsize;
max(dsize, datalength(name)) + 1 -> dsize;
pr_field(name, dsize, false, `\s`);
dsize; ;;; return dsize
else
cucharout(`\n`)
endif
enddefine;
;;; For each row, this procedure will be given nresultcols * 2
;;; arguments, the column value and dsize for each column
define pr_col(nargs);
lvars i;
for i from nargs by -2 to 2 do
pr_field(subscr_stack(i), subscr_stack(i), false, `\s`)
endfor;
erasenum(nargs);
cucharout(`\n`)
enddefine;
sql_app_result_set(hstmt, [{* ^Sql_P_string}], init_col,
pr_col);
endif;
sql_transact(hdbc);
sql_disconnect(hdbc)
enddefine;
--- C.all/ref/odbc
--- Copyright University of Sussex 1996. All rights reserved.