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

Syntax

Syntax Syntax

  1. <null predicate> ::= 
                            <column reference> IS ( NOT )? NULL.
End of the code.

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

Syntax Syntax

  1. SELECT * FROM a WHERE c IS NOT NULL
End of the code.

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

More Information

Column References