Firebird 2.1 Language Reference Update

Operators and predicates
if (New.Job is distinct from Old.Job)
then post_event 'job_changed';
IS [NOT] DISTINCT FROM always returns true or false, never NULL (unknown). The “=” and “” operators,
by contrast, return NULL if one or both operands are NULL. See also the table below.
Table 10.1. Comparison of [NOT] DISTINCT to “=” and “”
Operand characteristics
Results with the different operators
= NOT DISTINCT DISTINCT
Same value true true false false
Different values false false true true
Both NULL NULL true NULL false
One NULL NULL false NULL true
Available in: DSQL, PSQL
Added in: 2.0
NEXT VALUE FOR
Description: 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.
Syntax:
Example:
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 GEN_ID function.
See also: CREATE SEQUENCE, GEN_ID()
See ANY
SOME
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