Here are the areas you need to focus on while writing the COBOL VSAM program.

Select statement

SELECT FILE1     ASSIGN TO FILE1
                 ORGANIZATION IS INDEXED/RELATIVE
                 ACCESS MODE IS SEQUENTIAL/RANDOM/DYNAMIC
                 RECORD KEY IS MY-KEY/RELATIVE KEY IS MY_KEY
                 FILE STATUS IS FILE-STATUS.

File description

FD file-name 
      [BLOCK CONTAINS integer-1 RECORDS] 
      [RECORD CONTAINS integer-2 CHARACTERS].

Read: The List of VSAM File Status Codes

Open, Reading, writing

#To open the file
OPEN INPUT/OUTPUT/I-O/EXTEND FILE1.

#Sequential read till end of the file
READ file-name INTO data-name
    [AT END imperative-statement-1]
    [NOT AT END imperative-statement-2]
END-READ.

#To read random record from input file
MOVE 'ABCD'    TO MY-KEY.
READ file-name INTO data-name
    [INVALID KEY imperative-statement-1]
    [NOT INVALID KEY imperative-statement-2]
END-READ.

# To write a sequential record
WRITE record-name FROM data-name
END-WRITE.

# To write a random record
WRITE record-name FROM data-name
    [INVALID KEY imperative-statement-1]
    [NOT INVALID KEY imperative-statement-2]
END-WRITE.

Start Statement

START FILE1 KEY IS MY_KEY.

Closing files

CLOSE FILE-NAME.

Errors

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