Referencing a sequence object
A sequence object is a user-defined object that generates a sequence of numeric values according to the specification with which the sequence was created. You can retrieve the next or previous value in the sequence.
About this task
You reference a sequence by using the NEXT VALUE expression
or the PREVIOUS VALUE expression, specifying the name of the sequence:
- A NEXT VALUE expression generates and returns the next value for the specified sequence. If a query contains multiple instances of a NEXT VALUE expression with the same sequence name, the sequence value increments only once for that query. The ROLLBACK statement has no effect on values already generated.
- A PREVIOUS VALUE expression returns the most recently generated value for the specified sequence for a previous NEXT VALUE expression that specified the same sequence within the current application process. The value of the PREVIOUS VALUE expression persists until the next value is generated for the sequence, the sequence is dropped, or the application session ends. The COMMIT statement and the ROLLBACK statement have no effect on this value.
You can specify a NEXT VALUE or PREVIOUS VALUE expression in a SELECT clause, within a VALUES clause of an insert operation, within the SET clause of an update operation (with certain restrictions), or within a SET host-variable statement.
Parent topic: Accessing data from application programs