VALUE(x,y,...) 
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.
x, y, ... |
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 |
Example
SQL Tutorial, Converting Values