OCCURS DEPENDING ON













OCCURS DEPENDING ON


Using OCCURS clause we can define tables/arrays in cobol. 
For example if you want to store monthly profits for the year, 
you need to define 12 data items for each month
 
01	WS-PROFIT-JAN		PIC 9(05)V99.
01	WS-PROFIT-FEB		PIC 9(05)V99.
….
01	WS-PROFIT-DEC		PIC 9(05)V99.


Instead of declaring multiple data items we can specify field 
once and  declare that it repeats 12 times, one for each month.

01 WS-PROFIT    PIC 9(05)V99   OCCURS 12 TIMES.	 


WS-PROFIT(1) contain 1st month profit.
WS-PROFIT(2) contain 2nd month profit.
..
WS-PROFIT(12) contain 12th month profit.


Accessing array elements using numbers is called subscripting. 
(ie, WS-PROFIT(1) , here 1 is used to refer 1st element in array
, WS-PROFIT(2), here 2 is used to refer 2nd element in array..). 
Subscripting is a method of providing table references through 
the use of integer numbers as shown in below example.

 






The OCCURS can also be used at group level.

Example:

	01	WS-EMP-DATA	OCCURS 20 TIMES.
		05 WS-EMP-ID		PIC X(05).
		05 WS-EMP-NAME		PIC X(15).

In the above example OCCURS is at group level so entire group 
(employee id and employee name) occurs 20 times. 

Table data can also be arranged in ascending or descending order 
depending on data items specified. And we can also specify indexes 
that can be used with a table.


For example employee data can be arranged in employee id ascending 
order, and with index WS-INDEX.


  01  WS-EMP-DATA   OCCURS 20 TIMES ASCENDING KEY WS-EMP-ID
  		    INDEXED BY WS-INDEX.
      05 WS-EMP-ID		PIC X(05).
      05 WS-EMP-NAME		PIC X(15).




OCCURS….   DEPENDING ON:

Variable length tables can be specified using OCCURS DEPENDING ON 
clause. This allows tables to occur variable no of times depending 
on the value of some other field.



Example:

	01  WS-EMP-COUNT        PIC 9(03).	
	01  WS-EMP-DATA      OCCURS 1 TO 100 TIMES 
                             DEPENDING ON WS-EMP-COUNT
	    05 WS-EMP-ID		PIC X(05).
	    05 WS-EMP-NAME		PIC X(15).


In above example WS-EMP-DATA is variable length table. WS-EMP-DATA 
can have 1 to 100 employee records. The actual number of employee 
records depends on WS-EMP-COUNT value.

Size of the table depends on the number of table occurrences, i.e. 
WS-EMP-COUNT.  Minimum size occupied is 20 bytes and maximum is 
2000 bytes.