Database Functions

The following is a list of the 6 database DML functions:

Control statements:
- Initiate and terminate processing
- Effect recovery
- Prevent concurrent retrieval and update of database records
- Evaluate set conditions
Retrieval statements locate records in the database and make them available to the application program.
Modification statements add new records to the database and modify and delete existing records.
Accept statements move special information such as database keys, storage addresses, and statistics from the DBMS to program variable storage.
Logical-record statements retrieve, modify, store, and erase logical records.
Recovery statements perform functions relating to database, scratch, and queue area recovery in the event of a system failure. These functions:
- Establish checkpoints in the journal file for database, scratch, and queue records used by the issuing task
- Roll back user database, scratch, and queue areas to the last checkpoint established
- Establish an end-of-task checkpoint and relinquish control of all database, scratch, and queue areas associated with the issuing task
- Write user-defined records to the journal file