SQL/MX Programming Manual for C and COBOL (G06.24+, H06.03+)

Dynamic SQL With Descriptor Areas
HP NonStop SQL/MX Programming Manual for C and COBOL—523627-004
10-13
Steps for Using SQL Item Descriptor Areas
Figure 10-2 shows the steps presented within the complete COBOL program. These
steps are executed in the sample program Example C-4 on page C-9.
For more information:
1. Declare a Host Variable for the Dynamic SQL Statement on page 10-14
2. Construct the SQL Statement From User Input on page 10-14
3. Allocate Input and Output SQL Descriptor Areas on page 10-14
Figure 10-2. Using SQL Descriptor Areas in a COBOL Program
EXEC SQL BEGIN DECLARE SECTION;
01 hv-sql-statement PIC X(256).
01 in-value PIC 9(5) COMP.
01 num PIC 9(4) COMP.
* Declare host variables for item descriptor values.
01 num-data PIC S9(9) COMP.
01 char-data PIC X(100).
...
EXEC SQL END DECLARE SECTION;
* Construct the SQL statement from user input.
...
MOVE 1 TO desc-max.
EXEC SQL ALLOCATE DESCRIPTOR 'in_sqlda' WITH MAX :desc-max ...
MOVE 6 TO desc-max.
EXEC SQL ALLOCATE DESCRIPTOR 'out_sqlda' WITH MAX :desc-max ...
EXEC SQL PREPARE sqlstmt FROM :hv-sql-statement END-EXEC.
...
EXEC SQL DESCRIBE INPUT sqlstmt
USING SQL DESCRIPTOR 'in_sqlda' END-EXEC.
EXEC SQL DESCRIBE OUTPUT sqlstmt
USING SQL DESCRIPTOR 'out_sqlda' END-EXEC.
MOVE 1 TO desc-value.
EXEC SQL SET DESCRIPTOR 'in_sqlda' VALUE :desc-value
VARIABLE_DATA = :in-value END-EXEC.
EXEC SQL EXECUTE sqlstmt USING SQL DESCRIPTOR 'in_sqlda'
INTO SQL DESCRIPTOR 'out_sqlda' END-EXEC.
EXEC SQL GET DESCRIPTOR 'out_sqlda' :num = COUNT END-EXEC.
PERFORM VARYING i FROM 1 BY 1 UNTIL i > num
EXEC SQL GET DESCRIPTOR 'out_sqlda' VALUE :i
:type = TYPE,
:length = LENGTH,
:name = NAME
END-EXEC.
* Test type or name to determine the compatible host variable.
if ...
EXEC SQL GET DESCRIPTOR 'out_sqlda' VALUE :i
:num-data = VARIABLE_DATA
END-EXEC.
END-PERFORM.
* Process the values from the item descriptor areas.
EXEC SQL DEALLOCATE PREPARE sqlstmt END-EXEC.
EXEC SQL DEALLOCATE DESCRIPTOR 'in_sqlda' END-EXEC.
EXEC SQL DEALLOCATE DESCRIPTOR 'out_sqlda' END-EXEC.
COBOL
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