Operation Notes |
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The file to which the content of record is written must be open for output only if sequential mode is specified. It may be opened for output or input/output if the access mode at open is random or
dynamic.
When the file is opened for sequential access (access mode = 0) and for output only (I-O type = 1), then records must be written to the file in ascending sequential order by primary key value. The value of the primary key in the record to be written must be greater than the value of the primary key in any record previously written to the file. This ensures that the records written to the file are initially in ascending order physically as well as logically.
When I-O type = 1, CKWRITE writes records starting at the beginning of the file, thereby effectively clearing any records previously written to the file.
In a file opened for random or dynamic access (access mode = 1 or 2) and for output only or for input/output (I-O type = 1 or 2), records can be written in any order. The value of the primary key need not be in any particular relation to the primary key values of previously written records.
If you want to preserve existing records in the file, you should open the file with the input/output type equal to 2; when input/output type = 1, all existing records are cleared prior to the write.
If the file was opened for shared access with CKOPENSHR, then you must lock the file with a call to CKLOCK before writing any records. After the records are written, you should unlock the file with a call to CKUNLOCK.
The invalid key condition (left byte of status=2) can occur as a result of the following circumstances:
File was opened for sequential access in output mode and the value of the primary key in the record being written is less than or equal to the value of the primary key in the record just written; status=21.
File was opened for sequential or random access in output or input/output mode and the value of the primary key is equal to the value of the primary key in an existing record; status=22.
File was opened for sequential or random access in output or input/output mode and the value of an alternate key for which duplicates are prohibited equals the value of a corresponding key in an existing record; status=22.
File was opened for sequential or random access in output or input/output mode and an attempt was made to write a record beyond the physical bounds of the file; status=24.
Assume a KSAM file called KSAMFILE with records containing 74 characters, one primary key containing a name, and an alternate key containing a phone number. The data is read from an input file called DATA-FILE. (Refer to Figure A-2 “Representation of KSAMFILE Used in COBOL Examples” for a diagram of the structure of this file.)
The first example writes data to KSAMFILE in sequential order by the primary key.
DATA DIVISION
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WORKING-STORAGE SECTION.
77 RECSIZE PIC S9(4) COMP VALUE 74.
77 RESULT PIC 9(4) VALUE 0.
01 REC.
03 FILLER PIC XX VALUE SPACES.
03 NAME PIC X(20).
03 PHONE PIC X(8).
03 OTHERDATA PIC X(44).
01 DAT.
03 NAME PIC X(20).
03 PHONE PIC X(8).
03 OTHERDATA PIC X(44).
01 FILETABLE.
03 FILENUMBER PIC S9(4) COMP VALUE 0.
03 FILENAME PIC X(8) VALUE "KSAMFILE".
03 I-O-TYPE PIC S9(4) COMP VALUE 0.
03 A-MODE PIC S9(4) COMP VALUE 0.
03 PREV-OP PIC S9(4) COMP VALUE 0.
01 STAT.
03 STATUS-KEY-1 PIC X.
03 STATUS-KEY-2 PIC X.
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PROCEDURE DIVISION.
START.
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MOVE 1 TO I-O-TYPE,<--- set type to output only
CALL "CKOPEN" USING FILETABLE, STAT.
IF STATUS-KEY-1="O" THEN GO TO WRITE-F.
DISPLAY "CKOPEN ERROR, STATUS = ", STAT.
IF STATUS-KEY-1= "9" THEN
CALL "CKERROR" USING STAT, RESULT
DISPLAY "CKERROR NO. ", RESULT.
STOP RUN.
WRITE-F.
READ DATA-FILE INTO DAT;
AT END GO TO FINISH.
MOVE CORRESPONDING DAT TO REC.
CALL "CKWRITE" USING FILETABLE, STAT, REC, RECSIZE.
IF STATUS-KEY-1="0" THEN
DISPLAY REC.
GO TO WRITE-F.
IF STAT="21" THEN
DISPLAY "SEQUENCE ERROR IN", NAME OF REC
GO TO WRITE-F.
IF STAT = "22" THEN
DISPLAY "DUPLICATE KEY", NAME OF REC
GO TO WRITE-F.
IF STAT = "24" THEN
DISPLAY "END OF FILE"
GO TO FINISH.
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FINISH
CLOSE DATA-FILE.
CALL "CKCLOSE" USING FILETABLE, STAT.
IF STATUS-KEY-1="9" THEN
CALL "CKERROR" USING STAT, RESULT
DISPLAY "CKCLOSE ERROR NO. ", RESULT.
STOP RUN.
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The second example, using the same DATA DIVISION and the same FINISH procedure, writes one record to the file containing "ADAMSON JOHN" as its primary key value.
PROCEDURE DIVISION.
START.
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MOVE 1 TO I-O TYPE.<--- output only
MOVE 2 TO A-MODE.<--- random access
CALL "CKOPEN"USING FILETABLE, STAT.
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. check status
FIND-REC.
READ DATA-FILE INTO DAT;
AT END GO TO FINISH.
IF NAME OF DAT = "ADAMSON JOHN" THEN
GO TO WRlTE-REC;
ELSE GO TO FIND-REC.
WRITE-REC.
MOVE CORRESPONDING DAT TO REC.
CALL "CKWRITE" USING FILETABLE, STAT, REC, RECSIZE.
IF STATUS-KEY-1="0" THEN
DISPLAY REC," RECORD WRITTEN"
GO TO FINISH.
IF STAT = "22" THEN
DISPLAY "DUPLICATE KEY"
GO TO FINISH.
IF STAT = "24" THEN
DISPLAY "NO ROOM IN FILE"
GO TO FINISH.
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