# Flow Control Functions
+ `CASE` expression
+ `NULLIF()` function
+ `IFNULL()` function
+ `IF()` function

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- TiDB supports the use of all flow control functions provided in MySQL 5.7
  - `CASE`  Case operator
  - `IF()`  Build if/else
  - `IFNULL()`  Build Null if/else
  - `NULLIF()`  If expr1 = expr2, return NULL