Value « Sequences « Oracle PL/SQL Tutorial

5.6.1.Set start value, mini/max value and cache
5.6.2.Once initialized, you can get the current value from the sequence using currval.
5.6.3.When you select currval , nextval remains unchanged; nextval only changes when you select nextval to get the next value.
5.6.4.Query current sequence value
5.6.5.Get next value from sequence deptno_seq.currval, deptno_seq.nextval
5.6.7.Automatically including unique sequence numbers during an INSERT.
5.6.8.Use dual table to check sequence
5.6.9.Random value based on sequence

5.6.10.If id is null, use the value from sequence