Added in: 2.0
Returns the next value in a sequence.
SEQUENCE is the SQL-compliant term for what InterBase and Firebird have always called a generator.
NEXT VALUE FOR is fully equivalent to
GEN_ID(..., 1) and is the recommended syntax from Firebird 2.0 onward.
NEXT VALUE FOR sequence-name
new.cust_id = next value for custseq;
NEXT VALUE FOR doesn't support increment values other than 1. If you absolutely need other step values, use the legacy