Choice Functions
Choice functions provide a way to select from two values based on some characteristic of one of the values.
| Function | Definition | Datatype Constraint |
|---|---|---|
COALESCE(x,y+) |
Returns the first non-null parameter |
x and all y’s can be any compatible types |
IFNULL(x,y) |
If x is null, return y; else return x |
x, y, and the return type must be the same type but can be any type |
NVL(x,y) |
If x is null, return y; else return x |
x, y, and the return type must be the same type but can be any type |
NULLIF(param1, param2) |
Equivalent to case when (param1 = param2) then null else param1 |
param1 and param2 must be compatable comparable types |
IFNULL and NVL are aliases of each other. They are the same function.