# String Functions
+ Perform an operation on a string, for example:
  + Calculates string length
  + Extracting a substring
  + Search or replace a substring
  + Case conversion
+ A string function can return a numeric value or a string

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Note: REPEAT () can be used to generate large string and may be useful during the course. 

```
tidb> select repeat('xc',10);
+----------------------+
| repeat('xc',10)      |
+----------------------+
| xcxcxcxcxcxcxcxcxcxc |
+----------------------+
1 row in set (0.00 sec)
```

TiDB supports the use of most string function provided in MySQL 5.7.