Introduction to Navigational Programming › Retrieving Data › Retrieval Functions › WITHIN SET

WITHIN SET

Once entry is made into the database, the user program can locate additional records by following set linkages. The FIND/OBTAIN WITHIN SET function provides the following options for this purpose:

• FIRST- Locates the first member record in a set.
• LAST- Locates the last member record in a set (prior linkage required).
• Nth- Locates the nth member record in a set.
• NEXT- Locates the next record in a set.
• PRIOR- Locates the prior record in a set (prior linkage required).
• OWNER- Locates the owner record in a set (owner linkage recommended but not required).
• USING- Locates a record in a set by using its sort key value (sorted sets, including index sets, only).

The process of consecutively accessing member records within a set is called walking a set.

In a set containing multiple record types (for example, HOSPITAL-CLAIM, NON-HOSPITAL-CLAIM, and DENTAL-CLAIM which are all members of the COVERAGE-CLAIMS set), records can be located independently of record type, or the function can be limited to records of a specified record type.

The following figure illustrates various WITHIN SET options. Using our Commonweather example, we enter the database on John Done through the OBTAIN CALC function. We then use the OBTAIN WITHIN SET function to locate the first record in his EMP-COVERAGE set and then to locate various records in its COVERAGE-CLAIMS set.

In the following figure, the FIND/OBTAIN WITHIN SET function allows us to locate an employee that has at least an A skill rating in C++.