Entering content frame

NULL predicate 

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

Syntax

<null_predicate> ::= <expression> IS [NOT] NULL

expression

Explanation

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

 

Result of the function x IS NULL

x is NULL value

true

x is a special NULL value

false

 

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

Leaving content frame