How to: |
The Adapter for VSAM supports both direct and sequential retrieval of fixed- and variable-length records from RRDS files, as well as modification of those records. RRDS files are VSAM files that are accessed through Relative Record Number keys (RRNs) and are processed in basically the same manner as key-sequenced (KSDS or KSEQ) VSAM files.
The RRN field that serves as the primary (unique) key for the segment follows all real fields in the physical root segment of the Master File and establishes the sequence for the records. The RRN field description must contain the following attributes:
ALIAS=RRN, USAGE=I10, ACTUAL=I4
Records in RRDS files are processed sequentially if the request does not provide a screening condition or join for the RRN-associated field.
FILE=RRDSVSAM, SUFFIX=VSAM, DATASET=PGMYAN.RRDSVSAM.CLUSTER, $ SEGNAME=ROOT ,SEGTYPE=S0 ,$ FIELD=CODE , ,USAGE=A2 ,ACTUAL=A2 ,$ FIELD=NAME , ,USAGE=A10 ,ACTUAL=A10 ,$ FIELD=VALUE , ,USAGE=P2 ,ACTUAL=Z1 ,$ FIELD=ACCESS_KEY ,ALIAS=RRN ,USAGE=I10 ,ACTUAL=I4 ,$
The following examples show how to view and apply unique Relative Record Number (RRN) key values when working with records in RRDS files.
Printing the records with their key values
TABLE FILE RRDSVSAM PRINT CODE NAME VALUE ACCESS_KEY END
Screening records by unique key values
TABLE FILE RRDSVSAM PRINT CODE NAME VALUE ACCESS_KEY IF ACCESS_KEY GE 5 IF ACCESS_KEY LE 15 END
Retrieving records by unique key values
TABLE FILE RRDSVSAM PRINT CODE NAME VALUE ACCESS_KEY IF ACCESS_KEY EQ 5 OR 7 OR 9 END
Modifying records by unique key values
MODIFY FILE RRDSVSAM ECHO FREEFORM ACCESS_KEY MATCH ACCESS_KEY ON NOMATCH COMPUTE CODE = 'A1'; ON NOMATCH COMPUTE NAME = 'RECORD 20'; ON NOMATCH INCLUDE ON MATCH REJECT DATA ACCESS_KEY=20 END
Updating matching records in RRDS files by unique key values
MODIFY FILE RRDSVSAM ECHO FREEFORM ACCESS_KEY MATCH ACCESS_KEY ON NOMATCH REJECT ON MATCH TYPE "CODE: <D.CODE>, NAME: <D.NAME>, VALUE: <D.VALUE>"; ON MATCH COMPUTE VALUE = 9; ON MATCH UPDATE VALUE DATA ACCESS_KEY=20 END
Deleting RRDS records based on unique key values
MODIFY FILE RRDSVSAM ECHO FREEFORM ACCESS_KEY MATCH ACCESS_KEY ON NOMATCH REJECT ON MATCH TYPE "CODE: <D.CODE>, NAME: <D.NAME>, VALUE: <D.VALUE>"; ON MATCH DELETE DATA ACCESS_KEY=7 END
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