Compaq COBOL AAQ2G1FTK, Руководство пользователя

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Processing Files and Records
6.5 Updating Files
Example 6–39 (Cont.) Rewriting Relative Records in Random Access Mode
A100-UPDATE-RECORD.
DISPLAY "TO UPDATE A RECORD ENTER ITS RECORD NUMBER".
ACCEPT KETCHUP-MASTER-KEY.
READ FLAVORS INVALID KEY DISPLAY "BAD READ"
GO TO A005-EOJ.
DISPLAY "*********BEFORE UPDATE*********".
DISPLAY KETCHUP-MASTER.
********************************************************
*
*
Update routine
*
********************************************************
DISPLAY "*********AFTER UPDATE*********".
DISPLAY KETCHUP-MASTER.
REWRITE KETCHUP-MASTER INVALID KEY DISPLAY "BAD REWRITE"
GO TO A005-EOJ.
6.5.2.2 Deleting Records from a Relative File
The DELETE statement logically removes an existing record from a relative file.
After successfully removing a record from a file, the program cannot later access
it. Two options are available for deleting relative records:
• Sequential access mode deletion
• Random access mode deletion
Deleting A Relative Record in Sequential Access Mode
Deleting a relative record in sequential access mode involves the following:
1. Specifying ORGANIZATION IS RELATIVE in the Environment Division
SELECT clause
2. Specifying ACCESS MODE IS SEQUENTIAL in the Environment Division
SELECT clause
3. Opening the file for I-O
4. Using a START statement to position the record pointer, or sequentially
reading the file up to the target record
5. Deleting the last read record
Example 6–40 deletes relative records in sequential access mode.
Example 6–40 Deleting Relative Records in Sequential Access Mode
IDENTIFICATION DIVISION.
PROGRAM-ID. REL09.
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
SELECT FLAVORS ASSIGN TO "BRAND"
ORGANIZATION IS RELATIVE
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Processing Files and Records 6–53