Descendant Periodic Groups and Multi-value Fields

The ADABAS Interface must retrieve a count of the number of occurrences before attempting to retrieve a periodic group (PE) or multi-value (MU) field. This retrieval is accomplished by taking the appropriate ADABAS count field (indicated by the OCCURS attribute on the segment declaration in the Master File) and placing its ALIAS (the two-character ADABAS name of the PE or MU appended with the letter C) in the Format buffer of the call for the parent record fields.

ADABAS returns to this count field the total number of occurrences that exist for the PE or MU.

The ADABAS Interface retrieves the descendant data in one of the following ways:

• For MU fields or PE groups which do not contain an MU, all the occurrences are retrieved at once. The count field ALIAS is used without the letter C, to retrieve the entire set of occurrences in one Read ISN (L2) call.
• For PE groups which contain one or more MU fields, the Interface retrieves a single occurrence of all component fields at a time, including the count(s) of the number of MU descendants, if required. For example, a PE group containing an MU field which has five occurrences of the PE requires five Read ISN (L2) calls to retrieve all of them.