# CASE Expressions
__*CASE expression*__
+ For example:
  + **`SELECT CASE WHEN NULL='' THEN TRUE WHEN NULL<>'' THEN FALSE ELSE '=)' END;`**  
  + **`SELECT CASE NULL WHEN '' THEN TRUE WHEN 0 THEN FALSE ELSE '=)' END;`**  
```
tidb> SELECT 
   -> ~!@CASE@!~ 
   -> WHEN null='' THEN true 
   -> WHEN null<>'' THEN false 
   -> ELSE '=)' END;
+--------------------------------------------------------------------+
| CASE WHEN NULL='' THEN TRUE WHEN NULL<>'' THEN FALSE ELSE '=)' END |
+--------------------------------------------------------------------+
| =)                                                                 |
+--------------------------------------------------------------------+
1 row in set (0.00 sec)
tidb> SELECT 
   -> ~!@CASE NULL@!~ 
   -> WHEN '' THEN TRUE 
   -> WHEN 0 THEN FALSE 
   -> ELSE '=)' END;
+-------------------------------------------------------------+
| CASE NULL WHEN '' THEN TRUE WHEN 0 THEN FALSE ELSE '=)' END |
+-------------------------------------------------------------+
| =)                                                          |
+-------------------------------------------------------------+
1 row in set (0.00 sec)
```

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