Sorting and Merging Files
Arranging records in a particular sequence is a common requirement in data
processing. Such record sequencing can be accomplished using sort or merge
operations.
- The sort operation accepts unsequenced input and
produces output in a specified sequence.
- The merge operation compares two or more sequenced
files and combines them in sequential order.
To sort or merge files, you need to do the following:
- Describe the input and output files, if any, for sorting or merging.
- This is accomplished by selecting the files in the FILE-CONTROL paragraph
of the INPUT-OUTPUT SECTION and by describing the file using FD (File Description)
entries in the FILE SECTION of the DATA DIVISION.
- Describe the sort files and merge files.
- This is accomplished by selecting the sort or merge files in the FILE-CONTROL
paragraph of the INPUT-OUTPUT SECTION and by describing the file using SD
(Sort Description) entries in the FILE SECTION of the DATA DIVISION.
- Specify the sort or merge operation.
- This is accomplished by performing the SORT or MERGE statements in the
PROCEDURE DIVISION.
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