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Understanding Database Functions

Database functions provide the means of performing actions on the database. There are four different database functions each defining a HLL subroutine that creates, changes, deletes, or retrieves data. Database functions are implemented as part of an external standard function.

The four database functions are:

• Create Object (CRTOBJ)—Defines a routine to add a record to a file. It includes processing to check that the record does not already exist before writing to the database.
• Change Object (CHGOBJ)—Defines a routine to update a record on a file. It includes processing to check that the record already exists before updating the database record.
• Delete Object (DLTOBJ)—Defines a routine to delete a record from a database file. It includes processing to check that the record is still on the file before deleting it.
• Retrieve Object (RTVOBJ)—Defines a routine to retrieve one or more records from a database file. Processing can be specified for each record read by modifying the action diagram for the function.

A default version of the Create Change and Delete database functions is defined for all database files (REF and CPT). You must create the Retrieve Object function if you need it.

The following table includes the standard database functions.

All the CA 2E database functions have action diagrams that you can use to specify additional processing before and after the accessing the database .