#  SUBSTRING Retrieves Part Of A String
__*SUBSTRING function*__
+ `SUBSTRING(string, startpos [, length])`: Returns a substring whose length does not exceed the beginning of the character in**startpos** 
  + If**length** is omitted, the substring will include all characters at the end
  + If **startpos** is negative, the substring is return starting at the end
```10
tidb> SELECT substring('TiDB SQL', 2), substring('TiDB SQL', 1, 2), substring('TiDB SQL', -2, 2);
+--------------------------+-----------------------------+------------------------------+
| substring('TiDB SQL', 2) | substring('TiDB SQL', 1, 2) | substring('TiDB SQL', -2, 2) |
+--------------------------+-----------------------------+------------------------------+
| iDB SQL                  | Ti                          | QL                           |
+--------------------------+-----------------------------+------------------------------+
```

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- SUBSTRING () return the specified substring