Declaring an XSQLDA
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The extended SQL descriptor area (XSQLDA) is used as an intermediate staging area for information passed between an application and the InterBase engine. The XSQLDA is used for either of the following tasks:
- Pass input parameters from a host-language program to SQL.
- Pass output, from a
SELECTstatement or stored procedure, from SQL to the host-language program.
A single XSQLDA can be used for only one of these tasks at a time. Many applications declare two XSQLDAs, one for input, and another for output.
The XSQLDA structure is defined in the InterBase header file, ibase.h, that is automatically included in programs when they are preprocessed with gpre.
DSQL applications written using versions of InterBase prior to 3.3 use an older SQL descriptor area, the
SQLDA. The SQLDA and the gpre -sqlda switch are no longer supported. Older applications should be modified to use the XSQLDA.To create an XSQLDA for a program, a host-language data type of the appropriate type must be set up in a section declaration. For example, the following statement creates two XSQLDA structures, inxsqlda, and outxsqlda:
. . . EXEC SQL BEGIN DECLARE SECTION; XSQLDA inxsqlda; XSQLDA outxsqlda; . . . EXEC SQL END DECLARE SECTION; . . .
When an application containing XSQLDA declarations is preprocessed, gpre automatically includes the header file, ibase.h, which defines the XSQLDA as a host-language data type. For a complete discussion of the structure of the XSQLDA, see Using Dynamic SQL.