Handling InterBase Error Codes (Embedded SQL Guide)

Go Up to Additional InterBase Error Handling

Whenever SQLCODE is less than –1, the error status array, isc_status, may contain detailed error information specific to InterBase, including error codes, numbers that uniquely identify each error. With care, error-handling routines can trap for and respond to specific codes.

To trap and handle InterBase error codes in an error-handling routine, follow these steps:

Check SQLCODE to be sure it is less than –1.
Check that the first element of the status array is set to isc_arg_gds, indicating that an InterBase error code is available. In C programs, the first element of the status array is isc_status[0].
Do not attempt to handle errors reported in the status array if the first status array element contains a value other than 1.
If SQLCODE is less than –1 and the first element in isc_status is set to isc_arg_gds, use the actual InterBase error code in the second element of isc_status to branch to an appropriate routine for that error.

Tip:
InterBase error codes are mapped to mnemonic definitions (for example, isc_arg_gds) that can be used in code to make it easier to read, understand, and maintain. Definitions for all InterBase error codes can be found in the ibase.h file.

The following C code fragment illustrates an error-handling routine that:

Displays error messages with isc_print_sqlerror().
Illustrates how to parse for and handle six specific InterBase errors which might be corrected upon roll back, data entry, and retry.
Uses mnemonic definitions for InterBase error numbers.

. . .
int c, jval, retry_flag = 0;
jmp_buf jumper;
. . .
main()
{
. . .
jval = setjmp(jumper);
if (retry_flag)
ROLLBACK;
. . .
}
int ErrorHandler(void)
{
retry_flag = 0; /* reset to 0, no retry */
isc_print_sqlerror(SQLCODE, isc_status); /* display errors */
if (SQLCODE < –1)
{
if (isc_status[0] == isc_arg_gds)
{
switch (isc_status[1])
{
case isc_convert_error:
case isc_deadlock:
case isc_integ_fail:
case isc_lock_conflict:
case isc_no_dup:
case isc_not_valid:
printf("\n Do you want to try again? (Y/N)");
c = getchar();
if (c == 'Y' || c == 'y')
{
retry_flag = 1; /* set flag to retry */
longjmp(jumper, 1);
}
break;
case isc_end_arg: /* there really isn’t an error */
retry_flag = 1; /* set flag to retry */
longjump(jumper, 1);
break;
default: /* we can’t handle everything, so abort */
break;
}
}
}
EXEC SQL
ROLLBACK;
EXEC SQL
DISCONNECT ALL;
exit(1);
}

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