Ingres 11.2 | IS NULL Predicate

SQL Reference Guide > SQL Reference Guide > Understanding the Elements of SQL Statements > Predicates in SQL > IS NULL Predicate

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IS NULL Predicate

Use IS NULL to determine whether an expression is null, because you cannot test for null by using the = comparison operator. When applied to row value expressions, all elements must test the same.

The IS NULL predicate takes the following form:

IS [NOT] NULL

For example:

x IS NULL

is true if x is a null.

IS UNKNOWN is a synonym for IS NULL when the expression is of the BOOLEAN type.

Last modified date: 08/28/2024