Indicator variables used with host structures

If the results column values returned to a host structure can be null, you can add an indicator array name after the host structure name. This allows SQL to notify your program about each null value returned to a host variable in the host structure.

For example, in COBOL:

01  SAL-REC.
    10 MIN-SAL            PIC S9(6)V99 USAGE COMP-3.
    10 AVG-SAL            PIC S9(6)V99 USAGE COMP-3.
    10 MAX-SAL            PIC S9(6)V99 USAGE COMP-3.
01  SALTABLE.
02  SALIND                PIC S9999 USAGE COMP-4 OCCURS 3 TIMES.
01  EDUC-LEVEL            PIC S9999 COMP-4.
   …
    MOVE 20 TO EDUC-LEVEL.
   …
    EXEC SQL
     SELECT MIN(SALARY), AVG(SALARY), MAX(SALARY)
       INTO :SAL-REC:SALIND
       FROM CORPDATA.EMPLOYEE
       WHERE EDLEVEL>:EDUC-LEVEL
    END-EXEC.

In this example, SALIND is an array that contains three values, each of which can be tested for a negative value. SQL selects the values for the result row and puts them into the host structure. If MIN-SAL is to return a null value, the corresponding indicator variable, SALIND(1), is set to -1. Your program must check the corresponding indicator variables first to determine which, if any, selected result variables contain the null value.