Converting between Julian and Gregorian date formats

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DB2® supports a combination of industry and IBM® standard date formats. A local date format can be supported by a user-written exit routine. It is possible that the format you used when your VSAM files were designed may not match your chosen DB2 format.

A common requirement with CICS® VT customers is to convert Julian date fields to DB2 DATE columns.In the context of this manual, Julian and Gregorian date formats are defined as follows:

Julian date: This format of date is a combination of year plus a relative day number within the year, which is more correctly called an ordinal date. A typical example is 2013-348 in the format YYYYDDD. This is equivalent to a calendar date of December 14^th 2013.
Gregorian date: This format of date corresponds to any of the industry or IBM standard date formats supported by DB2. For example, the International Organization for Standardization (ISO) format is CCYY-MM-DD. 2013-12-14 is equivalent to the calendar date December 14^th 2013.

There is a sample assembler exit called JULGREG which is available for converting between Julian and Gregorian dates. It supports a VSAM field format of YYDDDHHMM. The COBOL exit CJULGRG that follows converts a 7-byte unsigned zoned decimal field with the format YYYYDDD into a DB2 date. It also performs the reverse.

COBOL code


 CBL LIB
 IDENTIFICATION DIVISION.
 PROGRAM-ID. CJULGRG.
*
* THIS FBE CONVERTS A 7-BYTE UNSIGNED ZONED DECIMAL FIELD IN
* VSAM TO A DB2 DATE COLUMN. NO DATA VERIFICATION IS PERFORMED.
*
 ENVIRONMENT DIVISION.
 DATA DIVISION.
 WORKING-STORAGE SECTION                .
 01 WS-DB2-FIELD               PIC 9(8) .
 01 WS-VSAM-FIELD              PIC 9(7) .
*
 01 WS-DB2-TEMP-FIELD                   .
    02 TEMP-YYYY               PIC 9(4) .
    02 TEMP-MM                 PIC 9(2) .
    02 TEMP-DD                 PIC 9(2) .
 01 WS-DB2-TEMP REDEFINES
    WS-DB2-TEMP-FIELD          PIC 9(8) .
*
 LINKAGE SECTION                        .
 01 VSAM-FIELD                 PIC 9(7) .
 01 DB2-FIELD                           .
    02 DB2-YYYY                PIC 9(4) .
    02 FILLER                  PIC X    .
    02 DB2-MM                  PIC 9(2) .
    02 FILLER                  PIC X    .
    02 DB2-DD                  PIC 9(2) .
    COPY VIDFBEC                        .
*
 PROCEDURE DIVISION USING VSAM-FIELD, DB2-FIELD, EXITPARMS .
 MAIN-SECTION.
    SET ADDRESS OF VSAM-FIELD TO EXVSAFLD.
    SET ADDRESS OF DB2-FIELD TO EXDB2FLD.
    EVALUATE EXFUNCT
       WHEN 'D'      PERFORM BUILD-DB2-FIELD
       WHEN 'V'      PERFORM BUILD-VSAM-FIELD
    END-EVALUATE .
 MAIN-SECTION-END.
    GOBACK.
    EXIT.
 BUILD-VSAM-FIELD SECTION.
 10-BUILD-VSAM-FIELD.
     MOVE DB2-YYYY    TO TEMP-YYYY .
     MOVE DB2-MM      TO TEMP-MM .
     MOVE DB2-DD      TO TEMP-DD .
     COMPUTE WS-VSAM-FIELD  =
             FUNCTION INTEGER-OF-DATE(WS-DB2-TEMP) .
     COMPUTE VSAM-FIELD =
             FUNCTION DAY-OF-INTEGER(WS-VSAM-FIELD).
 10-BUILD-VSAM-FIELD-END.
    EXIT.
 BUILD-DB2-FIELD SECTION.
 10-BUILD-DB2-FIELD.
     COMPUTE WS-DB2-FIELD      =
             FUNCTION INTEGER-OF-DAY(VSAM-FIELD).
     COMPUTE WS-DB2-TEMP       =
             FUNCTION DATE-OF-INTEGER(WS-DB2-FIELD).
     MOVE TEMP-YYYY    TO DB2-YYYY .
     MOVE TEMP-MM      TO DB2-MM .
     MOVE TEMP-DD      TO DB2-DD .
 10-BUILD-DB2-FIELD-END.
     EXIT.

Notes for CJULGRG

This is a very simple exit that uses COBOL intrinsic functions to handle the data conversion between Julian and Gregorian date formats. No verification of VSAM field values is performed.