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Procedure CKWRITE copies a logical record from the program's data area to an output or an
input-output file.
CALL "CKWRITE" USING filetable, status, record, recordsize
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A call to procedure CKWRITE may be used to write records to a KSAM file either in sequential
order or randomly by key value. The file must have been opened for output or for input-output,
but not for input only. PARAMETERS | |
- filetable
an 8-word record containing the number and name of the file, its
input-output type, access mode, and a code indicating whether the
previous operation on the file was successful and if so what it was.
(Refer to Filetable Parameter discussion earlier in this section.) - status
one-word (two 8-bit characters) set to a pair of values upon completion
of the call to CKWRITE to indicate whether or not the record was
successfully written and if not why not. (Refer to Status Parameter
discussion earlier in this section.) - record
a record defined in the WORKING-STORAGE SECTION containing
data to be written to the file by CKWRITE. - recordsize
an interger (S9(4)COMP) containing the length in characters of the
record to be written.lt must not exceed the maximum record length
established for the file when it was created, and it must be long enough
to contain all the keys.
USING CKWRITE | |
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. WRITING IN SEQUENTIAL MODE. 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 insures 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. WRITING IN RANDOM MODE. 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. WRITING WHEN ACCESS IS SHARED. 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. INVALID KEY. 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".
EXAMPLES | |
Assume a KSAM file called KSAMFILE with records containing 74 characters (72 characters of
data following two characters reserved for the delete code), 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 3-2 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. The second example, using the same DATA DIVISION and the same FINISH
procedure, writes one record to the file containing the "ADAMSON JOHN" as its
primary key value.
Example of Sequential Write.
DATA DIVISION
.
.
.
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.
.
.
.
PROCEDURE DIVISION.
START.
.
.
.
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.
.
.
.
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.
Example of random write.
PROCEDURE DIVISION.
START.
.
.
.
MOVE 1 TO I-O TYPE.<------------- output only
MOVE 2 TO A-MODE.<-------------- random access
CALL "CKOPEN"USING FILETABLE, STAT.
.
. 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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