A predicate specifies a condition that is true,
false, or unknown about a given
value,
row,
or group.
The following rules apply to all types of predicates:
- Predicates are evaluated after the expressions that are operands
of the predicate.
- All values specified in the same predicate must be compatible.
- The value of a variable may be null (that is, the variable may
have a negative indicator variable).
- The CCSID conversion of operands of predicates involving two or
more operands are done according to Conversion rules for comparison:.
- Use of a DataLink value is limited to the NULL predicate.
Row-value expression: The operand of several predicates
(basic, quantified, and IN) can be a row-value-expression:

.-,----------.
V |
>>-(----expression-+--)----------------------------------------><
A row-value-expression returns a single
row that consists of one or more column values. The values can be
specified as a list of expressions. The number of columns that are
returned by the row-value-expression is equal to the number
of expressions that are specified in the list.