Error Handling in Cobol
Textual error messages associated with each error number can be retrieved using the SQL statements GET DIAGNOSTICS and GET DIAGNOSTICS EXCEPTION. These can be declared in a subroutine which is called in the event of a returned non-zero SQLCODE. The COBOL program must declare a character variable to receive the error text, an integer variable containing the length of the error text, an integer variable containing the total number of error conditions available, and an integer variable containing the current error condition. These 4 items must be declared in a DECLARE SECTION, which is in scope whenever the above SQL statements are called. A programming example using GET DIAGNOSTICS / GET DIAGNOSTICS EXCEPTION looks like this:
000015 WORKING-STORAGE SECTION.
000016 EXEC SQL BEGIN DECLARE SECTION END-EXEC.
000017* Error Text Buffer
000018 01 ERRBUF PIC X(512).
000019* Length of Error Text Buffer
000020 01 ERRLEN PIC 9(9) COMP SYNC VALUE 512.
000021* Count of error conditions
000022 01 CONDITIONCOUNT PIC 9(9) COMP SYNC VALUE 0.
000023* Current error condition
000024 01 ERRNUMBER PIC 9(9) COMP SYNC VALUE 0.
000025 EXEC SQL END DECLARE SECTION END-EXEC.
000030 EXEC SQL INCLUDE SQLCA END-EXEC.
000045 PROCEDURE DIVISION.
000041 IF SQLCODE NOT = 0
000042* Obtain the count of error conditions to be returned in
000043* CONDITIONCOUNT
000044 EXEC SQL
000045 GET DIAGNOSTICS :CONDITIONCOUNT = NUMBER
000046 END-EXEC
000050 IF CONDITIONCOUNT > 0
000051* Obtain each error condition text CONDITIONCOUNT times
000052* The error condition text will be returned in ERRBUF
000053 PERFORM DOERROR
000054 VARYING ERRNUMBER FROM 1 BY 1
000055 UNTIL ERRNUMBER > CONDITIONCOUNT
000056 END-IF
000057 END-IF
000058*
000070* Subroutine DOERROR
000071*
000072 DOEXCEPTION.
000073 EXEC SQL
000074 GET DIAGNOSTICS EXCEPTION :ERRNUMBER
000075 :ERRBUF = MESSAGE_TEXT,
000076 :ERRLEN = MESSAGE_LENGTH
000077 END-EXEC
000078 DISPLAY "ERR MSG: " G-ERRBUF
000079
where

CONDITIONCOUNT | is the count of error conditions available, returned by GET DIAGNOSTICS.
ERRNUMBER | is the current error condition.
ERRBUF | is the target buffer, space filled on return from GET DIAGNOSTICS EXCEPTION.
ERRLEN | is the length of the target buffer ERRBUF.