The KEY concept represents fundamental record identification and file access mechanisms within COBOL file processing environments, providing sophisticated indexing capabilities that enable direct record access, efficient data retrieval, and optimized file organization patterns. These key specifications embody advanced file management principles by supporting multiple access paths, ensuring data integrity through unique identification, and facilitating high-performance database operations while maintaining VSAM compatibility, enabling complex search patterns, and providing comprehensive record positioning across enterprise applications requiring robust file processing, efficient data access, and scalable indexing architectures with reliable performance characteristics and optimized retrieval patterns.
12345678910111213141516171819202122232425262728293031323334353637383940414243444546*> FILE-CONTROL section key definitions SELECT file-name ASSIGN TO external-name ORGANIZATION IS INDEXED ACCESS MODE IS [SEQUENTIAL | RANDOM | DYNAMIC] RECORD KEY IS primary-key-field [ALTERNATE RECORD KEY IS alternate-key-field [WITH DUPLICATES]] [RELATIVE KEY IS relative-key-field] FILE STATUS IS file-status-field. *> Primary key (unique identifier) SELECT EMPLOYEE-FILE ASSIGN TO "EMPLOYEE.DAT" ORGANIZATION IS INDEXED ACCESS MODE IS DYNAMIC RECORD KEY IS EMP-ID ALTERNATE RECORD KEY IS EMP-SSN ALTERNATE RECORD KEY IS EMP-LAST-NAME WITH DUPLICATES FILE STATUS IS WS-EMP-STATUS. *> Relative key for relative files SELECT INVENTORY-FILE ASSIGN TO "INVENTORY.DAT" ORGANIZATION IS RELATIVE ACCESS MODE IS RANDOM RELATIVE KEY IS WS-RELATIVE-KEY FILE STATUS IS WS-INV-STATUS. *> Multiple alternate keys SELECT CUSTOMER-FILE ASSIGN TO "CUSTOMER.DAT" ORGANIZATION IS INDEXED ACCESS MODE IS DYNAMIC RECORD KEY IS CUST-ID ALTERNATE RECORD KEY IS CUST-PHONE ALTERNATE RECORD KEY IS CUST-EMAIL ALTERNATE RECORD KEY IS CUST-ACCOUNT-NUM WITH DUPLICATES FILE STATUS IS WS-CUST-STATUS. *> Key fields in record structure 01 EMPLOYEE-RECORD. 05 EMP-ID PIC 9(6). *> Primary key 05 EMP-SSN PIC 9(9). *> Alternate key 05 EMP-LAST-NAME PIC X(20). *> Alternate key with duplicates 05 EMP-FIRST-NAME PIC X(15). 05 EMP-DEPT PIC X(10). 05 EMP-SALARY PIC 9(8)V99. *> Working storage for relative key 01 WS-RELATIVE-KEY PIC 9(6).
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576IDENTIFICATION DIVISION. PROGRAM-ID. KEY-DEMONSTRATION. ENVIRONMENT DIVISION. INPUT-OUTPUT SECTION. FILE-CONTROL. *> Employee master file with multiple keys SELECT EMPLOYEE-MASTER ASSIGN TO "EMPLOYEE.DAT" ORGANIZATION IS INDEXED ACCESS MODE IS DYNAMIC RECORD KEY IS EMP-ID ALTERNATE RECORD KEY IS EMP-SSN ALTERNATE RECORD KEY IS EMP-LAST-NAME WITH DUPLICATES ALTERNATE RECORD KEY IS EMP-DEPT-ID WITH DUPLICATES FILE STATUS IS WS-EMP-STATUS. *> Product inventory with complex keys SELECT PRODUCT-INVENTORY ASSIGN TO "PRODUCT.DAT" ORGANIZATION IS INDEXED ACCESS MODE IS DYNAMIC RECORD KEY IS PROD-ID ALTERNATE RECORD KEY IS PROD-UPC ALTERNATE RECORD KEY IS PROD-SKU ALTERNATE RECORD KEY IS PROD-CATEGORY WITH DUPLICATES FILE STATUS IS WS-PROD-STATUS. *> Customer orders with relative organization SELECT ORDER-FILE ASSIGN TO "ORDERS.DAT" ORGANIZATION IS RELATIVE ACCESS MODE IS DYNAMIC RELATIVE KEY IS WS-ORDER-RELATIVE-KEY FILE STATUS IS WS-ORDER-STATUS. *> Transaction log with date-based keys SELECT TRANSACTION-LOG ASSIGN TO "TRANS.DAT" ORGANIZATION IS INDEXED ACCESS MODE IS SEQUENTIAL RECORD KEY IS TRANS-KEY ALTERNATE RECORD KEY IS TRANS-DATE WITH DUPLICATES ALTERNATE RECORD KEY IS TRANS-ACCOUNT WITH DUPLICATES FILE STATUS IS WS-TRANS-STATUS. DATA DIVISION. FILE SECTION. FD EMPLOYEE-MASTER. 01 EMPLOYEE-RECORD. 05 EMP-ID PIC 9(6). 05 EMP-SSN PIC 9(9). 05 EMP-PERSONAL-INFO. 10 EMP-LAST-NAME PIC X(20). 10 EMP-FIRST-NAME PIC X(15). 10 EMP-MIDDLE-INIT PIC X. 05 EMP-WORK-INFO. 10 EMP-DEPT-ID PIC X(5). 10 EMP-JOB-TITLE PIC X(25). 10 EMP-HIRE-DATE PIC 9(8). 10 EMP-SALARY PIC 9(8)V99. 05 EMP-CONTACT-INFO. 10 EMP-PHONE PIC 9(10). 10 EMP-EMAIL PIC X(50). 10 EMP-ADDRESS PIC X(100). FD PRODUCT-INVENTORY. 01 PRODUCT-RECORD. 05 PROD-ID PIC X(12). 05 PROD-UPC PIC 9(12). 05 PROD-SKU PIC X(15). 05 PROD-DESCRIPTION PIC X(50). 05 PROD-CATEGORY PIC X(20). 05 PROD-PRICING. 10 PROD-COST PIC 9(8)V99. 10 PROD-PRICE PIC 9(8)V99. 10 PROD-DISCOUNT PIC 9(3)V99. 05 PROD-INVENTORY. 10 PROD-QTY-HAND PIC 9(8). 10 PROD-QTY-RESERVED PIC 9(8). 10 PROD-REORDER-POINT PIC 9(6). FD ORDER-FILE. 01 ORDER-RECORD. 05 ORDER-ID PIC 9(10). 05 ORDER-DATE PIC 9(8). 05 ORDER-CUSTOMER-ID PIC 9(8). 05 ORDER-STATUS PIC X(10). 05 ORDER-TOTAL PIC 9(10)V99. 05 ORDER-ITEMS-COUNT PIC 9(3). FD TRANSACTION-LOG. 01 TRANSACTION-RECORD. 05 TRANS-KEY. 10 TRANS-DATE PIC 9(8). 10 TRANS-TIME PIC 9(6). 10 TRANS-SEQUENCE PIC 9(6). 05 TRANS-ACCOUNT PIC 9(10). 05 TRANS-TYPE PIC X(10). 05 TRANS-AMOUNT PIC S9(10)V99. 05 TRANS-DESCRIPTION PIC X(50). 05 TRANS-REFERENCE PIC X(20). WORKING-STORAGE SECTION. *> File status fields 01 WS-FILE-STATUS-FIELDS. 05 WS-EMP-STATUS PIC X(2). 05 WS-PROD-STATUS PIC X(2). 05 WS-ORDER-STATUS PIC X(2). 05 WS-TRANS-STATUS PIC X(2). *> Key fields for file operations 01 WS-KEY-FIELDS. 05 WS-SEARCH-EMP-ID PIC 9(6). 05 WS-SEARCH-SSN PIC 9(9). 05 WS-SEARCH-NAME PIC X(20). 05 WS-SEARCH-DEPT PIC X(5). 05 WS-ORDER-RELATIVE-KEY PIC 9(6). 05 WS-SEARCH-PROD-ID PIC X(12). 05 WS-SEARCH-UPC PIC 9(12). 05 WS-SEARCH-CATEGORY PIC X(20). *> Browse control fields 01 WS-BROWSE-CONTROL. 05 WS-CURRENT-KEY PIC X(50). 05 WS-PREVIOUS-KEY PIC X(50). 05 WS-RECORDS-READ PIC 9(6) VALUE 0. 05 WS-END-OF-FILE PIC X VALUE 'N'. *> Counters and flags 01 WS-COUNTERS. 05 WS-EMPLOYEE-COUNT PIC 9(6) VALUE 0. 05 WS-PRODUCT-COUNT PIC 9(6) VALUE 0. 05 WS-ORDER-COUNT PIC 9(6) VALUE 0. 05 WS-OPERATION-COUNT PIC 9(8) VALUE 0. PROCEDURE DIVISION. MAIN-PROCESSING. PERFORM OPEN-FILES PERFORM DEMONSTRATE-PRIMARY-KEY-ACCESS PERFORM DEMONSTRATE-ALTERNATE-KEY-ACCESS PERFORM DEMONSTRATE-RELATIVE-KEY-ACCESS PERFORM DEMONSTRATE-SEQUENTIAL-KEY-PROCESSING PERFORM DEMONSTRATE-KEY-POSITIONING PERFORM DEMONSTRATE-DUPLICATE-KEY-HANDLING PERFORM CLOSE-FILES STOP RUN. OPEN-FILES. DISPLAY "=== OPENING FILES ===" OPEN I-O EMPLOYEE-MASTER IF WS-EMP-STATUS NOT = "00" DISPLAY "Error opening Employee file: " WS-EMP-STATUS STOP RUN END-IF OPEN I-O PRODUCT-INVENTORY IF WS-PROD-STATUS NOT = "00" DISPLAY "Error opening Product file: " WS-PROD-STATUS STOP RUN END-IF OPEN I-O ORDER-FILE IF WS-ORDER-STATUS NOT = "00" DISPLAY "Error opening Order file: " WS-ORDER-STATUS STOP RUN END-IF DISPLAY "All files opened successfully" DISPLAY SPACES. DEMONSTRATE-PRIMARY-KEY-ACCESS. DISPLAY "=== PRIMARY KEY ACCESS ===" *> Direct access using primary key MOVE 123456 TO WS-SEARCH-EMP-ID MOVE WS-SEARCH-EMP-ID TO EMP-ID READ EMPLOYEE-MASTER INVALID KEY DISPLAY "Employee not found: " WS-SEARCH-EMP-ID NOT INVALID KEY DISPLAY "Employee found: " EMP-ID " " EMP-FIRST-NAME " " EMP-LAST-NAME DISPLAY "Department: " EMP-DEPT-ID DISPLAY "Salary: $" EMP-SALARY ADD 1 TO WS-EMPLOYEE-COUNT END-READ *> Product lookup by primary key MOVE "WIDGET-A-001" TO WS-SEARCH-PROD-ID MOVE WS-SEARCH-PROD-ID TO PROD-ID READ PRODUCT-INVENTORY INVALID KEY DISPLAY "Product not found: " WS-SEARCH-PROD-ID NOT INVALID KEY DISPLAY "Product found: " PROD-ID " - " PROD-DESCRIPTION DISPLAY "Category: " PROD-CATEGORY DISPLAY "Price: $" PROD-PRICE DISPLAY "Quantity: " PROD-QTY-HAND ADD 1 TO WS-PRODUCT-COUNT END-READ DISPLAY SPACES. DEMONSTRATE-ALTERNATE-KEY-ACCESS. DISPLAY "=== ALTERNATE KEY ACCESS ===" *> Search by SSN (alternate key) MOVE 123456789 TO WS-SEARCH-SSN MOVE WS-SEARCH-SSN TO EMP-SSN READ EMPLOYEE-MASTER KEY IS EMP-SSN INVALID KEY DISPLAY "Employee SSN not found: " WS-SEARCH-SSN NOT INVALID KEY DISPLAY "Employee found by SSN: " EMP-SSN DISPLAY "ID: " EMP-ID " Name: " EMP-FIRST-NAME " " EMP-LAST-NAME ADD 1 TO WS-EMPLOYEE-COUNT END-READ *> Search by last name (alternate key with duplicates) MOVE "SMITH" TO WS-SEARCH-NAME MOVE WS-SEARCH-NAME TO EMP-LAST-NAME READ EMPLOYEE-MASTER KEY IS EMP-LAST-NAME INVALID KEY DISPLAY "No employee with last name: " WS-SEARCH-NAME NOT INVALID KEY DISPLAY "Employee found by name: " EMP-LAST-NAME DISPLAY "ID: " EMP-ID " Full name: " EMP-FIRST-NAME " " EMP-LAST-NAME ADD 1 TO WS-EMPLOYEE-COUNT END-READ *> Product search by UPC MOVE 123456789012 TO WS-SEARCH-UPC MOVE WS-SEARCH-UPC TO PROD-UPC READ PRODUCT-INVENTORY KEY IS PROD-UPC INVALID KEY DISPLAY "Product UPC not found: " WS-SEARCH-UPC NOT INVALID KEY DISPLAY "Product found by UPC: " PROD-UPC DISPLAY "ID: " PROD-ID " Description: " PROD-DESCRIPTION ADD 1 TO WS-PRODUCT-COUNT END-READ DISPLAY SPACES. DEMONSTRATE-RELATIVE-KEY-ACCESS. DISPLAY "=== RELATIVE KEY ACCESS ===" *> Access order by relative record number MOVE 1 TO WS-ORDER-RELATIVE-KEY READ ORDER-FILE INVALID KEY DISPLAY "No order at relative position: " WS-ORDER-RELATIVE-KEY NOT INVALID KEY DISPLAY "Order found at position: " WS-ORDER-RELATIVE-KEY DISPLAY "Order ID: " ORDER-ID DISPLAY "Date: " ORDER-DATE DISPLAY "Customer: " ORDER-CUSTOMER-ID DISPLAY "Status: " ORDER-STATUS DISPLAY "Total: $" ORDER-TOTAL ADD 1 TO WS-ORDER-COUNT END-READ *> Try different relative positions PERFORM VARYING WS-ORDER-RELATIVE-KEY FROM 2 BY 1 UNTIL WS-ORDER-RELATIVE-KEY > 5 READ ORDER-FILE INVALID KEY DISPLAY "No order at position: " WS-ORDER-RELATIVE-KEY NOT INVALID KEY DISPLAY "Order " WS-ORDER-RELATIVE-KEY ": " ORDER-ID " ($" ORDER-TOTAL ")" ADD 1 TO WS-ORDER-COUNT END-READ END-PERFORM DISPLAY SPACES. DEMONSTRATE-SEQUENTIAL-KEY-PROCESSING. DISPLAY "=== SEQUENTIAL KEY PROCESSING ===" *> Sequential read of employee file MOVE "N" TO WS-END-OF-FILE MOVE 0 TO WS-RECORDS-READ START EMPLOYEE-MASTER KEY IS GREATER THAN OR EQUAL TO EMP-ID INVALID KEY DISPLAY "Cannot start sequential processing" MOVE "Y" TO WS-END-OF-FILE END-START PERFORM UNTIL WS-END-OF-FILE = "Y" OR WS-RECORDS-READ >= 10 READ EMPLOYEE-MASTER NEXT RECORD AT END MOVE "Y" TO WS-END-OF-FILE NOT AT END ADD 1 TO WS-RECORDS-READ DISPLAY "Seq " WS-RECORDS-READ ": " EMP-ID " " EMP-LAST-NAME ", " EMP-FIRST-NAME END-READ END-PERFORM DISPLAY "Sequential read completed. Records read: " WS-RECORDS-READ DISPLAY SPACES. DEMONSTRATE-KEY-POSITIONING. DISPLAY "=== KEY POSITIONING ===" *> Position using START statement MOVE "D" TO EMP-LAST-NAME(1:1) MOVE SPACES TO EMP-LAST-NAME(2:) START EMPLOYEE-MASTER KEY IS GREATER THAN OR EQUAL TO EMP-LAST-NAME INVALID KEY DISPLAY "Cannot position at names starting with 'D'" NOT INVALID KEY DISPLAY "Positioned at first name >= 'D'" *> Read next few records PERFORM 5 TIMES READ EMPLOYEE-MASTER NEXT RECORD AT END EXIT PERFORM NOT AT END DISPLAY " " EMP-LAST-NAME ", " EMP-FIRST-NAME " (ID: " EMP-ID ")" END-READ END-PERFORM END-START *> Position in product file by category MOVE "ELECTRONICS" TO PROD-CATEGORY START PRODUCT-INVENTORY KEY IS EQUAL TO PROD-CATEGORY INVALID KEY DISPLAY "No products in ELECTRONICS category" NOT INVALID KEY DISPLAY "Positioned at ELECTRONICS products" PERFORM 3 TIMES READ PRODUCT-INVENTORY NEXT RECORD AT END EXIT PERFORM NOT AT END IF PROD-CATEGORY = "ELECTRONICS" DISPLAY " " PROD-ID ": " PROD-DESCRIPTION " ($" PROD-PRICE ")" ELSE EXIT PERFORM END-IF END-READ END-PERFORM END-START DISPLAY SPACES. DEMONSTRATE-DUPLICATE-KEY-HANDLING. DISPLAY "=== DUPLICATE KEY HANDLING ===" *> Process all employees in a department (duplicate key) MOVE "IT" TO WS-SEARCH-DEPT MOVE WS-SEARCH-DEPT TO EMP-DEPT-ID START EMPLOYEE-MASTER KEY IS EQUAL TO EMP-DEPT-ID INVALID KEY DISPLAY "No employees in department: " WS-SEARCH-DEPT NOT INVALID KEY DISPLAY "Processing employees in department: " WS-SEARCH-DEPT PERFORM UNTIL 1 = 0 READ EMPLOYEE-MASTER NEXT RECORD AT END EXIT PERFORM NOT AT END IF EMP-DEPT-ID = WS-SEARCH-DEPT DISPLAY " " EMP-ID ": " EMP-FIRST-NAME " " EMP-LAST-NAME DISPLAY " Salary: $" EMP-SALARY ELSE EXIT PERFORM END-IF END-READ END-PERFORM END-START *> Process products by category (duplicate key) MOVE "TOOLS" TO WS-SEARCH-CATEGORY MOVE WS-SEARCH-CATEGORY TO PROD-CATEGORY START PRODUCT-INVENTORY KEY IS EQUAL TO PROD-CATEGORY INVALID KEY DISPLAY "No products in category: " WS-SEARCH-CATEGORY NOT INVALID KEY DISPLAY "Processing products in category: " WS-SEARCH-CATEGORY PERFORM UNTIL 1 = 0 READ PRODUCT-INVENTORY NEXT RECORD AT END EXIT PERFORM NOT AT END IF PROD-CATEGORY = WS-SEARCH-CATEGORY DISPLAY " " PROD-ID ": " PROD-DESCRIPTION DISPLAY " Price: $" PROD-PRICE " Qty: " PROD-QTY-HAND ELSE EXIT PERFORM END-IF END-READ END-PERFORM END-START DISPLAY SPACES. *> Advanced key operations ADVANCED-KEY-OPERATIONS. DISPLAY "=== ADVANCED KEY OPERATIONS ===" PERFORM DEMONSTRATE-KEY-RANGES PERFORM DEMONSTRATE-PARTIAL-KEY-MATCHING PERFORM DEMONSTRATE-KEY-VALIDATION. DEMONSTRATE-KEY-RANGES. DISPLAY "Key Range Processing:" *> Process employees with IDs in specific range MOVE 100000 TO EMP-ID START EMPLOYEE-MASTER KEY IS GREATER THAN OR EQUAL TO EMP-ID PERFORM UNTIL WS-END-OF-FILE = "Y" READ EMPLOYEE-MASTER NEXT RECORD AT END MOVE "Y" TO WS-END-OF-FILE NOT AT END IF EMP-ID <= 200000 DISPLAY "Range employee: " EMP-ID " " EMP-LAST-NAME ELSE MOVE "Y" TO WS-END-OF-FILE END-IF END-READ END-PERFORM. DEMONSTRATE-PARTIAL-KEY-MATCHING. DISPLAY "Partial Key Matching:" *> Find products with IDs starting with specific prefix MOVE "WIDGET" TO PROD-ID(1:6) MOVE SPACES TO PROD-ID(7:) START PRODUCT-INVENTORY KEY IS GREATER THAN OR EQUAL TO PROD-ID PERFORM 5 TIMES READ PRODUCT-INVENTORY NEXT RECORD AT END EXIT PERFORM NOT AT END IF PROD-ID(1:6) = "WIDGET" DISPLAY "Widget product: " PROD-ID ELSE EXIT PERFORM END-IF END-READ END-PERFORM. DEMONSTRATE-KEY-VALIDATION. DISPLAY "Key Validation:" 01 WS-VALIDATION-RESULTS. 05 WS-VALID-KEYS PIC 9(4) VALUE 0. 05 WS-INVALID-KEYS PIC 9(4) VALUE 0. *> Validate a series of employee IDs PERFORM VARYING WS-SEARCH-EMP-ID FROM 100000 BY 1000 UNTIL WS-SEARCH-EMP-ID > 110000 MOVE WS-SEARCH-EMP-ID TO EMP-ID READ EMPLOYEE-MASTER INVALID KEY ADD 1 TO WS-INVALID-KEYS NOT INVALID KEY ADD 1 TO WS-VALID-KEYS END-READ END-PERFORM DISPLAY "Key validation results:" DISPLAY "Valid keys : " WS-VALID-KEYS DISPLAY "Invalid keys: " WS-INVALID-KEYS. CLOSE-FILES. DISPLAY "=== CLOSING FILES ===" CLOSE EMPLOYEE-MASTER CLOSE PRODUCT-INVENTORY CLOSE ORDER-FILE DISPLAY "Summary:" DISPLAY "Employees processed: " WS-EMPLOYEE-COUNT DISPLAY "Products processed : " WS-PRODUCT-COUNT DISPLAY "Orders processed : " WS-ORDER-COUNT DISPLAY "Total operations : " WS-OPERATION-COUNT. *> Error handling for key operations KEY-ERROR-HANDLING. EVALUATE WS-EMP-STATUS WHEN "00" CONTINUE WHEN "02" DISPLAY "Duplicate key error" WHEN "22" DISPLAY "Duplicate alternate key" WHEN "23" DISPLAY "Record not found" WHEN "24" DISPLAY "Boundary violation" WHEN OTHER DISPLAY "File error: " WS-EMP-STATUS END-EVALUATE. *> Key maintenance operations KEY-MAINTENANCE-OPERATIONS. DISPLAY "=== KEY MAINTENANCE ===" PERFORM ADD-NEW-RECORDS PERFORM UPDATE-EXISTING-RECORDS PERFORM DELETE-RECORDS. ADD-NEW-RECORDS. DISPLAY "Adding new records with key validation:" *> Add new employee with unique key MOVE 999999 TO EMP-ID MOVE 987654321 TO EMP-SSN MOVE "JOHNSON" TO EMP-LAST-NAME MOVE "MIKE" TO EMP-FIRST-NAME MOVE "IT" TO EMP-DEPT-ID MOVE 65000.00 TO EMP-SALARY WRITE EMPLOYEE-RECORD INVALID KEY DISPLAY "Cannot add employee - key conflict: " EMP-ID PERFORM KEY-ERROR-HANDLING NOT INVALID KEY DISPLAY "Employee added successfully: " EMP-ID ADD 1 TO WS-OPERATION-COUNT END-WRITE. UPDATE-EXISTING-RECORDS. DISPLAY "Updating records by key:" *> Update employee salary MOVE 123456 TO EMP-ID READ EMPLOYEE-MASTER INVALID KEY DISPLAY "Employee not found for update: " EMP-ID NOT INVALID KEY ADD 5000.00 TO EMP-SALARY REWRITE EMPLOYEE-RECORD INVALID KEY DISPLAY "Update failed for employee: " EMP-ID NOT INVALID KEY DISPLAY "Employee updated: " EMP-ID " New salary: $" EMP-SALARY ADD 1 TO WS-OPERATION-COUNT END-REWRITE END-READ. DELETE-RECORDS. DISPLAY "Deleting records by key:" *> Delete specific employee MOVE 999999 TO EMP-ID READ EMPLOYEE-MASTER INVALID KEY DISPLAY "Employee not found for deletion: " EMP-ID NOT INVALID KEY DELETE EMPLOYEE-MASTER INVALID KEY DISPLAY "Delete failed for employee: " EMP-ID NOT INVALID KEY DISPLAY "Employee deleted: " EMP-ID ADD 1 TO WS-OPERATION-COUNT END-DELETE END-READ.
123456789101112131415161718FILE-CONTROL. SELECT CUSTOMER-FILE ASSIGN TO "CUSTOMER.DAT" ORGANIZATION IS INDEXED ACCESS MODE IS DYNAMIC RECORD KEY IS CUST-ID ALTERNATE RECORD KEY IS CUST-EMAIL ALTERNATE RECORD KEY IS CUST-PHONE ALTERNATE RECORD KEY IS CUST-LAST-NAME WITH DUPLICATES FILE STATUS IS WS-CUST-STATUS. 01 CUSTOMER-RECORD. 05 CUST-ID PIC 9(8). *> Primary key 05 CUST-EMAIL PIC X(50). *> Unique alternate key 05 CUST-PHONE PIC 9(10). *> Unique alternate key 05 CUST-LAST-NAME PIC X(25). *> Duplicate alternate key 05 CUST-FIRST-NAME PIC X(20). 05 CUST-ADDRESS PIC X(100). 05 CUST-CREDIT-LIMIT PIC 9(8)V99.
123456789101112131415161718192021222324252627282930313233343536373839PROCEDURE DIVISION. FIND-CUSTOMER-BY-ID. MOVE 12345678 TO CUST-ID READ CUSTOMER-FILE INVALID KEY DISPLAY "Customer not found: " CUST-ID NOT INVALID KEY DISPLAY "Customer: " CUST-FIRST-NAME " " CUST-LAST-NAME DISPLAY "Email: " CUST-EMAIL END-READ. FIND-CUSTOMER-BY-EMAIL. MOVE "john@example.com" TO CUST-EMAIL READ CUSTOMER-FILE KEY IS CUST-EMAIL INVALID KEY DISPLAY "No customer with email: " CUST-EMAIL NOT INVALID KEY DISPLAY "Found customer: " CUST-ID " " CUST-FIRST-NAME END-READ. BROWSE-CUSTOMERS-BY-NAME. MOVE "SMITH" TO CUST-LAST-NAME START CUSTOMER-FILE KEY IS EQUAL TO CUST-LAST-NAME INVALID KEY DISPLAY "No customers with name: " CUST-LAST-NAME NOT INVALID KEY PERFORM UNTIL 1 = 0 READ CUSTOMER-FILE NEXT RECORD AT END EXIT PERFORM NOT AT END IF CUST-LAST-NAME = "SMITH" DISPLAY " " CUST-ID ": " CUST-FIRST-NAME " " CUST-LAST-NAME ELSE EXIT PERFORM END-IF END-READ END-PERFORM END-START.
What's the difference between primary and alternate keys?
Answer: Primary keys (RECORD KEY) uniquely identify records and are required for indexed files. Alternate keys (ALTERNATE RECORD KEY) provide additional access paths and can optionally allow duplicates using WITH DUPLICATES clause.
How do you read a record using an alternate key?
Answer: Use "READ filename KEY IS alternate-key-name" to access records via alternate keys. The key field must be populated with the search value before the READ operation.
When should you use WITH DUPLICATES on alternate keys?
Answer: Use WITH DUPLICATES when multiple records can have the same alternate key value, such as last names, department codes, or categories. This allows multiple records to share the same alternate key value.