Processing Files and Records
6.3 Creating and Processing Files

Table6–5 ValidI/O Statements for Relative Files

Open Mode
File
Organization Access
Mode Statement INPUT OUTPUT I-O EXTEND
RELATIVE SEQUENTIAL DELETE
READ
REWRITE
START
WRITE
UNLOCK
No
Yes
No
Yes
No
Yes
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
No
No
No
No
Yes
Yes
RANDOM DELETE
READ
REWRITE
WRITE
UNLOCK
No
Yes
No
No
Yes
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
DYNAMIC DELETE
READ
READ NEXT
REWRITE
START
WRITE
UNLOCK
No
Yes
Yes
No
Yes
No
Yes
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
No

Writing a Relative File

Each WRITE statement places a record into a cell that contains no valid data. If

the cell does not already exist, the I/O system creates it. To change the contents

of a cell that already contains valid data, use the REWRITE statement.

6.3.4 FileHandling for Indexed Files

Creating an indexed file involves the following tasks:

1. Specifying ORGANIZATION IS INDEXED in the Environment Division

SELECT clause

2. Specifying ACCESS MODE IS SEQUENTIAL (or RANDOM or DYNAMIC) in

the Environment Division SELECT clause

3. Opening the file for OUTPUT (to create and add records) or for I-O (to add,

change, delete, or extend records)

4. Initializing the key values

5. Executing a WRITE statement

6. Closing the file

One way to populate an indexed file is to sequentially write the records in

ascending order by primary key. Example 6–26 creates and populates an indexed

file from a sequential file, which has been sorted in ascending sequence on the

primary key field. Notice that the primary and alternate keys are initialized in

ICE-CREAM-MASTER when the contents of the fields in INPUT-RECORD are

read into ICE-CREAM-MASTER before the record is written.

6–32 Processing Files and Records