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Declaring the SQLCA
The SQL Communication Area (SQLCA) is an ALLBASE/SQL data structure that
contains current information about a program's DBE session.
Every ALLBASE/SQL FORTRAN program unit that contains embedded SQL
statements must contain an SQLCA declaration. When a main program unit
or a subprogram unit starts a DBE session, the SQLCA declaration must be
in its Type Declaration Section. If a subprogram unit is called by a
main program and each contains SQL commands to be executed in the same
DBE session, the SQLCA declaration must appear in both the main program
and the subprogram units.
As shown in Figure 3-1 at 1, you declare the SQLCA by using the INCLUDE
command:
EXEC SQL INCLUDE SQLCA
When the FORTRAN preprocessor parses this command in the source file, it
generates a complete FORTRAN declaration for this area. Some of the
fields in the SQLCA are available for programmers to use:
SQLCODE
SQLERRD(3)
SQLWARN(0)
SQLWARN(1)
SQLWARN(2)
SQLWARN(6)
Some values ALLBASE/SQL places into these fields indicate warning and
error conditions that resulted when the immediately preceding SQL command
was executed. Other values simply provide information about normal
command execution and are programmatically useful. For example, when you
submit an UPDATE command, the number of rows updated is placed in
SQLERRD(3). If this value is greater than 1, the program may want to
advise the user of that condition and process a ROLLBACK WORK or COMMIT
WORK command based on the user's response.
Examples discussed later in this chapter under "Implicit Status Checking"
and "Explicit Status Checking" illustrate how the program in Figure 3-1
uses some of the SQLCA fields to determine the success or failure of SQL
command execution.