SQL update null values

Caution. You cannot use simple case to test for null because it always uses the equals operator ( = ). That is because the condition null = null is not true5—consequently, a when null clause never applies. If the <common operand> is null , the else clause applies .

The Greek lowercase omega (ω) character is used to represent Null in database theory.

You also can specify the NULL keyword in the VALUES clause to indicate that a column should be assigned a NULL value . The following example inserts values into three columns of the orders table: INSERT INTO orders (orders_num, order_date, customer_num) VALUES (0, NULL, 123);