Keyword for the NULL value

The keyword for the NULL value is NULL. NULL can only be specified during INSERT, MERGE and UPDATE operations, in a CAST expression, in a CASE expression and as the DEFAULT in column definitions to set a column value to the NULL value.

Example

You enter an item whose color is unknown into the ITEMS table as follows:

INSERT INTO items VALUES (5, 'Valve', NULL, 1.00, 350, 100)

NULL can also be specified in predicates (search queries, IF statement), as the default value of local variables (in routines), and in SET and RETURN statements.