COBOL SORT Statement - Quick Reference

The SORT statement in COBOL is used to arrange records in a specified order using the COBOL SORT utility. It provides efficient external sorting capabilities for large datasets that cannot be sorted in memory.

Primary Use

Sort records in files using external sort utility

Division

PROCEDURE DIVISION

File Type

Sequential files with SD definition

Performance

External sorting for large datasets

Overview

The SORT statement is a powerful COBOL feature that uses the external SORT utility to arrange records in a specified order. It is designed for processing large datasets that cannot be sorted in memory and provides efficient external sorting capabilities. SORT works with sequential files and uses temporary sort-merge files managed by the SORT utility.

Syntax

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SORT sort-file-name
    ON ASCENDING KEY sort-key-1 [sort-key-2 ...]
    ON DESCENDING KEY sort-key-3 [sort-key-4 ...]
    [USING input-file-1 [input-file-2 ...]]
    [GIVING output-file-1 [output-file-2 ...]]
    [INPUT PROCEDURE procedure-name-1 [THROUGH procedure-name-2]]
    [OUTPUT PROCEDURE procedure-name-3 [THROUGH procedure-name-4]]

Practical Examples

Basic SORT Operation

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* Basic SORT with single key
IDENTIFICATION DIVISION.
PROGRAM-ID. BASIC-SORT-EXAMPLE.
 
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
    SELECT UNSORTED-FILE ASSIGN TO "UNSORTED.DAT"
        ORGANIZATION IS SEQUENTIAL.
    SELECT SORTED-FILE ASSIGN TO "SORTED.DAT"
        ORGANIZATION IS SEQUENTIAL.
    SELECT SORT-WORK-FILE ASSIGN TO "SORTWORK".
 
DATA DIVISION.
FILE SECTION.
SD  SORT-WORK-FILE.
01  SORT-RECORD.
    05  SORT-EMPLOYEE-ID    PIC X(6).
    05  SORT-EMPLOYEE-NAME  PIC X(25).
    05  SORT-SALARY         PIC 9(8)V99.
 
FD  UNSORTED-FILE.
01  UNSORTED-RECORD.
    05  UNSORTED-EMPLOYEE-ID    PIC X(6).
    05  UNSORTED-EMPLOYEE-NAME  PIC X(25).
    05  UNSORTED-SALARY         PIC 9(8)V99.
 
FD  SORTED-FILE.
01  SORTED-RECORD.
    05  SORTED-EMPLOYEE-ID      PIC X(6).
    05  SORTED-EMPLOYEE-NAME    PIC X(25).
    05  SORTED-SALARY           PIC 9(8)V99.
 
PROCEDURE DIVISION.
MAIN-LOGIC.
    * Sort by employee ID in ascending order
    SORT SORT-WORK-FILE
        ON ASCENDING KEY SORT-EMPLOYEE-ID
        USING UNSORTED-FILE
        GIVING SORTED-FILE
    
    DISPLAY "Sort completed successfully"
    STOP RUN.

Explanation: This example demonstrates a basic SORT operation that sorts employee records by employee ID in ascending order. The SORT statement uses the SORT-WORK-FILE (defined with SD) as temporary storage, reads from UNSORTED-FILE, and writes the sorted results to SORTED-FILE. The ON ASCENDING KEY clause specifies the sort order and key field.

Multi-Key SORT Operation

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* Multi-key SORT with mixed ordering
IDENTIFICATION DIVISION.
PROGRAM-ID. MULTI-KEY-SORT-EXAMPLE.
 
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
    SELECT SALES-FILE ASSIGN TO "SALES.DAT"
        ORGANIZATION IS SEQUENTIAL.
    SELECT SORTED-SALES-FILE ASSIGN TO "SORTED-SALES.DAT"
        ORGANIZATION IS SEQUENTIAL.
    SELECT SORT-WORK-FILE ASSIGN TO "SORTWORK".
 
DATA DIVISION.
FILE SECTION.
SD  SORT-WORK-FILE.
01  SORT-RECORD.
    05  SORT-REGION           PIC X(2).
    05  SORT-SALESPERSON      PIC X(25).
    05  SORT-SALES-AMOUNT     PIC 9(8)V99.
    05  SORT-DATE             PIC X(8).
 
FD  SALES-FILE.
01  SALES-RECORD.
    05  SALES-REGION          PIC X(2).
    05  SALES-SALESPERSON     PIC X(25).
    05  SALES-AMOUNT          PIC 9(8)V99.
    05  SALES-DATE            PIC X(8).
 
FD  SORTED-SALES-FILE.
01  SORTED-SALES-RECORD.
    05  SORTED-REGION         PIC X(2).
    05  SORTED-SALESPERSON    PIC X(25).
    05  SORTED-SALES-AMOUNT   PIC 9(8)V99.
    05  SORTED-DATE           PIC X(8).
 
PROCEDURE DIVISION.
MAIN-LOGIC.
    * Sort by region (ascending), then by sales amount (descending)
    SORT SORT-WORK-FILE
        ON ASCENDING KEY SORT-REGION
        ON DESCENDING KEY SORT-SALES-AMOUNT
        USING SALES-FILE
        GIVING SORTED-SALES-FILE
    
    DISPLAY "Multi-key sort completed successfully"
    STOP RUN.

Explanation: This example demonstrates a multi-key SORT operation that sorts sales records first by region in ascending order, then by sales amount in descending order within each region. This creates a report where regions are ordered alphabetically, and within each region, salespeople are ordered by their sales amounts from highest to lowest.

SORT with INPUT PROCEDURE

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* SORT with INPUT PROCEDURE for data filtering
IDENTIFICATION DIVISION.
PROGRAM-ID. SORT-INPUT-PROC-EXAMPLE.
 
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
    SELECT MASTER-FILE ASSIGN TO "MASTER.DAT"
        ORGANIZATION IS SEQUENTIAL.
    SELECT SORTED-FILE ASSIGN TO "SORTED.DAT"
        ORGANIZATION IS SEQUENTIAL.
    SELECT SORT-WORK-FILE ASSIGN TO "SORTWORK".
 
DATA DIVISION.
FILE SECTION.
SD  SORT-WORK-FILE.
01  SORT-RECORD.
    05  SORT-CUSTOMER-ID      PIC X(10).
    05  SORT-CUSTOMER-NAME    PIC X(30).
    05  SORT-BALANCE          PIC 9(8)V99.
    05  SORT-STATUS           PIC X(1).
 
FD  MASTER-FILE.
01  MASTER-RECORD.
    05  MASTER-CUSTOMER-ID    PIC X(10).
    05  MASTER-CUSTOMER-NAME  PIC X(30).
    05  MASTER-BALANCE        PIC 9(8)V99.
    05  MASTER-STATUS         PIC X(1).
 
FD  SORTED-FILE.
01  SORTED-RECORD.
    05  SORTED-CUSTOMER-ID    PIC X(10).
    05  SORTED-CUSTOMER-NAME  PIC X(30).
    05  SORTED-BALANCE        PIC 9(8)V99.
    05  SORTED-STATUS         PIC X(1).
 
WORKING-STORAGE SECTION.
01  WS-EOF-FLAG              PIC X(1) VALUE 'N'.
 
PROCEDURE DIVISION.
MAIN-LOGIC.
    * Sort with INPUT PROCEDURE to filter active customers
    SORT SORT-WORK-FILE
        ON ASCENDING KEY SORT-CUSTOMER-NAME
        INPUT PROCEDURE SELECT-ACTIVE-CUSTOMERS
        GIVING SORTED-FILE
    
    DISPLAY "Sort with input procedure completed"
    STOP RUN.
 
SELECT-ACTIVE-CUSTOMERS.
    OPEN INPUT MASTER-FILE
    PERFORM UNTIL WS-EOF-FLAG = 'Y'
        READ MASTER-FILE
            AT END MOVE 'Y' TO WS-EOF-FLAG
            NOT AT END
                * Only include active customers (status = 'A')
                IF MASTER-STATUS = 'A'
                    MOVE MASTER-RECORD TO SORT-RECORD
                    RELEASE SORT-RECORD
                END-IF
        END-READ
    END-PERFORM
    CLOSE MASTER-FILE.

Explanation: This example demonstrates SORT with an INPUT PROCEDURE that filters data before sorting. The SELECT-ACTIVE-CUSTOMERS procedure reads the master file and only releases records for active customers (status = 'A') to the sort operation. This allows for data filtering and transformation before the actual sorting occurs, making the SORT operation more efficient by processing only relevant data.

SORT with OUTPUT PROCEDURE

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* SORT with OUTPUT PROCEDURE for custom processing
IDENTIFICATION DIVISION.
PROGRAM-ID. SORT-OUTPUT-PROC-EXAMPLE.
 
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
    SELECT INPUT-FILE ASSIGN TO "INPUT.DAT"
        ORGANIZATION IS SEQUENTIAL.
    SELECT REPORT-FILE ASSIGN TO "REPORT.DAT"
        ORGANIZATION IS SEQUENTIAL.
    SELECT SORT-WORK-FILE ASSIGN TO "SORTWORK".
 
DATA DIVISION.
FILE SECTION.
SD  SORT-WORK-FILE.
01  SORT-RECORD.
    05  SORT-DEPARTMENT       PIC X(3).
    05  SORT-EMPLOYEE-ID      PIC X(6).
    05  SORT-SALARY           PIC 9(8)V99.
    05  SORT-YEARS-SERVICE    PIC 99.
 
FD  INPUT-FILE.
01  INPUT-RECORD.
    05  INPUT-DEPARTMENT      PIC X(3).
    05  INPUT-EMPLOYEE-ID     PIC X(6).
    05  INPUT-SALARY          PIC 9(8)V99.
    05  INPUT-YEARS-SERVICE   PIC 99.
 
FD  REPORT-FILE.
01  REPORT-RECORD.
    05  REPORT-LINE           PIC X(80).
 
WORKING-STORAGE SECTION.
01  WS-EOF-FLAG              PIC X(1) VALUE 'N'.
01  WS-DEPARTMENT-TOTAL      PIC 9(10)V99 VALUE ZERO.
01  WS-CURRENT-DEPT          PIC X(3) VALUE SPACES.
 
PROCEDURE DIVISION.
MAIN-LOGIC.
    * Sort with OUTPUT PROCEDURE for custom report generation
    SORT SORT-WORK-FILE
        ON ASCENDING KEY SORT-DEPARTMENT
        ON DESCENDING KEY SORT-SALARY
        USING INPUT-FILE
        OUTPUT PROCEDURE GENERATE-DEPARTMENT-REPORT
    
    DISPLAY "Sort with output procedure completed"
    STOP RUN.
 
GENERATE-DEPARTMENT-REPORT.
    OPEN OUTPUT REPORT-FILE
    PERFORM UNTIL WS-EOF-FLAG = 'Y'
        RETURN SORT-WORK-FILE
            AT END MOVE 'Y' TO WS-EOF-FLAG
            NOT AT END
                * Check for department change
                IF SORT-DEPARTMENT NOT = WS-CURRENT-DEPT
                    * Write department total if not first department
                    IF WS-CURRENT-DEPT NOT = SPACES
                        MOVE WS-DEPARTMENT-TOTAL TO REPORT-LINE
                        WRITE REPORT-RECORD
                    END-IF
                    * Start new department
                    MOVE SORT-DEPARTMENT TO WS-CURRENT-DEPT
                    MOVE ZERO TO WS-DEPARTMENT-TOTAL
                    MOVE "Department: " TO REPORT-LINE(1:12)
                    MOVE SORT-DEPARTMENT TO REPORT-LINE(13:3)
                    WRITE REPORT-RECORD
                END-IF
                * Add salary to department total
                ADD SORT-SALARY TO WS-DEPARTMENT-TOTAL
                * Write employee record
                MOVE SORT-EMPLOYEE-ID TO REPORT-LINE(1:6)
                MOVE SORT-SALARY TO REPORT-LINE(20:10)
                WRITE REPORT-RECORD
        END-RETURN
    END-PERFORM
    * Write final department total
    IF WS-CURRENT-DEPT NOT = SPACES
        MOVE WS-DEPARTMENT-TOTAL TO REPORT-LINE
        WRITE REPORT-RECORD
    END-IF
    CLOSE REPORT-FILE.

Explanation: This example demonstrates SORT with an OUTPUT PROCEDURE that generates a custom report during the sort output phase. The GENERATE-DEPARTMENT-REPORT procedure processes sorted records and creates a department summary report with totals. It tracks department changes and accumulates salary totals, showing how OUTPUT PROCEDURE can be used for custom processing of sorted data.

Best Practices and Considerations

Important Considerations

Always define sort files with SD statements in the FILE SECTION
Ensure sufficient disk space for sort-merge files
Use appropriate sort keys for optimal performance
Consider using INPUT/OUTPUT procedures for data filtering and custom processing
Test sort operations with various data sizes and key combinations

Advantages

Efficient external sorting for large datasets
Uses optimized SORT utility
Supports multiple sort keys with different orders
Provides INPUT/OUTPUT procedures for custom processing
Handles datasets too large for memory sorting

Limitations

Requires temporary disk space
Limited to sequential file processing
Performance depends on disk I/O speed
Cannot sort in memory like table operations
Requires proper file definitions and error handling

Performance Tips

• Choose sort keys carefully to minimize sort complexity
• Use INPUT PROCEDURE to filter data before sorting
• Ensure adequate disk space for sort-merge files
• Monitor sort performance and resource usage
• Consider using OUTPUT PROCEDURE for custom processing

Test Your Knowledge

1. What is the primary purpose of the SORT statement in COBOL?

To sort data in memory
To sort records in files using external sort utility
To sort programs
To sort memory

2. In which COBOL division is the SORT statement typically used?

IDENTIFICATION DIVISION
ENVIRONMENT DIVISION
DATA DIVISION
PROCEDURE DIVISION

3. What is the relationship between SORT and SD statements?

They are unrelated
SD defines the sort file, SORT uses it
SORT defines the file, SD uses it
They are the same thing

4. Can SORT be used with all file types?

Yes, with all file types
No, only with sequential files
No, only with indexed files
Only with specific file types

5. What is the difference between SORT and internal table sorting?

They are the same thing
SORT uses external utility, table sorting uses memory
SORT is faster than table sorting
SORT is obsolete, table sorting is modern

COBOL Tutorial

COBOL SORT Statement - Quick Reference

Primary Use

Division

File Type

Performance

Overview

Syntax

Practical Examples

Basic SORT Operation

Multi-Key SORT Operation

SORT with INPUT PROCEDURE

SORT with OUTPUT PROCEDURE

Best Practices and Considerations

Important Considerations

Advantages

Limitations

Performance Tips

Test Your Knowledge

Related Concepts

SD Statement

SORT-MERGE Statement

File Processing

Data Organization

External Sort Utility

Related Pages

COBOL Tutorial

COBOL SORT Statement - Quick Reference

Primary Use

Division

File Type

Performance

Overview

Syntax

Practical Examples

Basic SORT Operation

Multi-Key SORT Operation

SORT with INPUT PROCEDURE

SORT with OUTPUT PROCEDURE

Best Practices and Considerations

Important Considerations

Advantages

Limitations

Performance Tips

Test Your Knowledge

Frequently Asked Questions

Related Concepts

SD Statement

SORT-MERGE Statement

File Processing

Data Organization

External Sort Utility

Related Pages