SQL Reference

Predicates

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

Supported predicats are as follows:

• Basic Predicate

• Quantified Predicate

• BETWEEN Predicate

• EXISTS Predicate

• IN Predicate

• LIKE Predicate

• NULL Predicate

• TYPE Predicate

The following rules apply to all types of predicates:

• All values specified in a predicate must be compatible.

• An expression used in a Basic, Quantified, IN, or BETWEEN predicate must not result in a character string with a length attribute greater than 4 000, a graphic string with a length attribute greater than 2 000, or a LOB string of any size.

• The value of a host variable may be null (that is, the variable may have a negative indicator variable).

• The code page conversion of operands of predicates involving two or more operands, with the exception of LIKE, are done according to Rules for String Conversions

• Use of a DATALINK value is limited to the NULL predicate.

A fullselect is a form of the SELECT statement which is described under Chapter 5, Queries. A fullselect used in a predicate is also called a subquery.

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