# **Overview of Control Flow Functions**

| Name | Description |
|---|----|
| [CASE](case-when.md) | CASE WHEN statement is used to calculate a list of conditions and return one of multiple possible result expressions |
| [IF()](function_if.md) | IF(expr1,expr2,expr3), when expr1 is TRUE, it returns expr2; otherwise, it returns expr3 |
| [IFNULL()](function_ifnull.md) | IFNULL(expr1,expr2), when expr1 is not NULL, it returns expr1; otherwise it returns expr2 |
| [NULLIF()](function_nullif.md) | NULLIF(expr1,expr2), when expr1 = expr2, returns NULL; otherwise, returns the value of expr1 |