Null predicate 

The null predicate is used to test if a column contains a NULL value.

Syntax

<null predicate> ::=                             <column reference> IS ( NOT )? NULL.

 

The <null predicate> "colref IS NOT NULL" is equivalent to the <boolean factor> "NOT colref IS NULL".

The result of the <null predicate> "colref IS NULL" is true if the value of the <column reference> colref is the NULL value, otherwise the result of the <null predicate> is false.

Example

SELECT * FROM a WHERE c IS NOT NULL

The IS NULL Predicate. This query yields all rows from table a where the column a.c is not the NULL value.

See

Column References