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Background documentationNULL Predicate (null_predicate)

 

By specifying a NULL predicate, (null_predicate) you can test whether the value is a NULL value.

Structure

Syntax Syntax

  1. <null_predicate> ::=
  <expression> IS [NOT] NULL
End of the code.
Examples

SQL Tutorial, Negative Conditions: NOT

Explanation

The truth content of a NULL predicate is either true or false.

NULL Predicate (null_predicate)

x

Result of the Function x IS NULL

x is a NULL value

True

x is a special NULL value

False

x IS NOT NULL has the same result as NOT(x IS NULL).