NULL operators

To check whether a value is or is not NULL, use the constructs:.

To check whether a value is or is not NULL, use the constructs:

[expression IS NULL | expression IS NOT NULL]

Alternatively, use equivalent, but nonstandard, constructs:

[expression ISNULL | expression NOTNULL]

Do not write expression = NULL because NULL represents an unknown value, and two unknown values are not necessarily equal. This behavior conforms to the SQL standard.

Note

Some applications might expect that expression = NULL returns true if expression evaluates to null. Vertica strongly recommends that these applications be modified to comply with the SQL standard.