A C or C++ program can be written to use the SQLCA to check return status for embedded SQL statements, or the program can use the SQL diagnostics area to check return status.
When using the SQLCA, a C or C++ program that contains SQL statements must include one or both of the following:
- An SQLCODE variable declared as long SQLCODE
- An SQLSTATE variable declared as char SQLSTATE[6]
Or,
- An SQLCA (which contains an SQLCODE and SQLSTATE variable).
The SQLCODE and SQLSTATE values are set by the database manager after each SQL statement is run. An application can check the SQLCODE or SQLSTATE value to determine whether the last SQL statement was successful.
You can code the SQLCA in a C or C++ program
directly or by using the SQL INCLUDE statement. When coding it directly, initialize
the SQLCA using the following statement: 
struct sqlca sqlca = {0x0000000000000000};
Using the SQL INCLUDE statement requests the inclusion of a standard declaration:
EXEC SQL INCLUDE SQLCA ;
A standard declaration includes a structure definition
and a data area that are named sqlca.
The SQLCODE, SQLSTATE, and SQLCA variables must appear before any executable statements. The scope of the declaration must include the scope of all SQL statements in the program.
The included C and C++ source statements for the SQLCA are:
#ifndef SQLCODE
struct sqlca {
unsigned char sqlcaid[8];
long sqlcabc;
long sqlcode;
short sqlerrml;
unsigned char sqlerrmc[70];
unsigned char sqlerrp[8];
long sqlerrd[6];
unsigned char sqlwarn[11];
unsigned char sqlstate[5];
};
#define SQLCODE sqlca.sqlcode
#define SQLWARN0 sqlca.sqlwarn[0]
#define SQLWARN1 sqlca.sqlwarn[1]
#define SQLWARN2 sqlca.sqlwarn[2]
#define SQLWARN3 sqlca.sqlwarn[3]
#define SQLWARN4 sqlca.sqlwarn[4]
#define SQLWARN5 sqlca.sqlwarn[5]
#define SQLWARN6 sqlca.sqlwarn[6]
#define SQLWARN7 sqlca.sqlwarn[7]
#define SQLWARN8 sqlca.sqlwarn[8]
#define SQLWARN9 sqlca.sqlwarn[9]
#define SQLWARNA sqlca.sqlwarn[10]
#define SQLSTATE sqlca.sqlstate
#endif
struct sqlca sqlca = {0x0000000000000000};