# 逆向、连接

__*CONCAT 函数*__
__*CANCAT_WS 函数*__
__*REVERSE 函数*__

+ `CONCAT(), CONCAT_WS()`: 将给定的参数连接成一个字符串
+ `REVERSE()`: 返回字符串,字符的顺序相反
+ 例如: 
  + `SELECT reverse('placeholder'), concat('hello ','world'), concat_ws(':','pingcap','cmg','pe');` 
```
tidb> SELECT reverse('placeholder'), concat('hello ','world'), concat_ws('~!@:@!~','pingcap','cmg','pe');
+------------------------+--------------------------+-------------------------------------+
| reverse('placeholder') | concat('hello ','world') | concat_ws(':','pingcap','cmg','pe') |
+------------------------+--------------------------+-------------------------------------+
| redlohecalp            | hello world              | pingcap:cmg:pe                      |
+------------------------+--------------------------+-------------------------------------+
1 row in set (0.00 sec)
```
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- CONCAT()	返回连接的字符串
- CONCAT_WS()	返回由分隔符连接的字符串