Predicates

Predicates

A predicate specifies a condition that is "true" or "false" about a given row or group.

Note: In SQL, string comparisons are strictly byte-for-byte, so predicates involving MIXED strings may not give the desired results. For instance, a string with the SBCS version of XYZ does not compare as equal to a string with a Shift-Out, then the DBCS version of XYZ, then a Shift-In. You can use the VARGRAPHIC scalar function to normalize both strings into VARGRAPHIC data types before doing the comparison.

Following is the syntax diagram for a predicate:

►►─┬─ basic predicate ──────┬─────────────────────────────────────────────────►◄
   ├─ quantified predicate ─┤
   ├─ BETWEEN predicate ────┤
   ├─ LIKE predicate ───────┤
   ├─ EXISTS predicate ─────┤
   ├─ IN predicate ─────────┤
   └─ NULL predicate ───────┘

All values specified in a predicate must be compatible.

The following sections discuss branches of the predicate's general form.