Modifying Action Diagrams › Understanding Contexts › System Contexts › *Record Data Changed

*Record Data Changed

The *Record Data Changed PGM context field specifies whether the data for the current record has changed. The value *Yes means the record data has changed; the value *No means that the record data has not changed; it is initialized to ‘ ‘ (blank). The database record is updated only when the value of this field is *Yes.

Note: Checking for unchanged record data is done only if the Null Update Suppression function option is Y or A.

You can access the *Record Data Changed field from all functions that contain an embedded CHGOBJ function, such as EDTFIL and EDTTRN. It is valid only in the Data Read and Data Update user points in the action diagram of CHGOBJ functions; other uses give invalid results. Two ways to use this field are:

• You can test its value to conditionally perform actions that depend on whether data has been changed as shown in the example following.
• You can manually set this field to conditionally force or suppress a database record update.

The following example illustrates a common technique for setting an audit stamp. The field, Timestamp, is set to the current date and time only if other fields within the record have been changed. In other words, if the value of the *Record Data Changed field is *Yes, then the audit stamp is written to the file.

The Timestamp field has the following characteristics:

• It is of type TS#.
• It is on the update access path for the CHGOBJ function.
• It is a Neither parameter on the CHGOBJ function, which means it is not passed into the routine and must be set by the action diagram code within CHGOBJ.

  > USER: Processing before Data update
  .—                                                         <<<
  :.> Only set the Timestamp field if other data has changed <<<
  :.—CASE                                                    <<<
  :|—PGM.*Record Data Changed is *Yes                        <<<
  :| DB1.Timestamp=JOB.*Job date                             <<<
  :| DB1.Timestamp=JOB.*Job time                             <<<
  :’—ENDCASE                                                 <<<
  ‘—

For more information on the CHGOBJ function, see this module, in the chapter "Defining Functions," CHGOBJ—Database Function topic.