VALUE(x,y,...) is a special function that can be used to replace NULL values with a non-NULL value.

The arguments (expressions) of the VALUE function must be comparable. The expressions are evaluated one after the other in the specified order.

Result of the VALUE(x,y,...) function

One of the arguments is a non-NULL value

The first non-NULL value that occurs

Each argument is a special NULL value

Special NULL value

Each argument is a NULL value

NULL value


SQL Tutorial, Converting Values