---
{
    "title": "substring",
    "language": "en"
}
---

<!-- 
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License.  You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied.  See the License for the
specific language governing permissions and limitations
under the License.
-->

## substring
### description
#### Syntax

`VARCHAR substring(VARCHAR str, INT pos[, INT len])`

The forms without a `len` argument return a substring from string `str` starting at position `pos`. 
The forms with a `len` argument return a substring len characters long from string `str`, starting at position pos. 
It is also possible to use a negative value for `pos`. In this case, 
the beginning of the substring is `pos` characters from the end of the string, rather than the beginning. 
A negative value may be used for `pos` in any of the forms of this function. 
A value of 0 for `pos` returns an empty string.

For all forms of SUBSTRING(), 
the position of the first character in the string from which the substring is to be extracted is reckoned as 1.

If len is less than 1, the result is the empty string.
### example

```
mysql> select substring('abc1', -2);
+-----------------------------+
| substring('abc1', 2)        |
+-----------------------------+
| bc1                         |
+-----------------------------+

mysql> select substring('abc1', -2);
+-----------------------------+
| substring('abc1', -2)       |
+-----------------------------+
| c1                          |
+-----------------------------+

mysql> select substring('abc1', 5);
+-----------------------------+
| substring('abc1', 5)        |
+-----------------------------+
| NULL                        |
+-----------------------------+

mysql> select substring('abc1def', 2, 2);
+-----------------------------+
| substring('abc1def', 2, 2)  |
+-----------------------------+
| bc                          |
+-----------------------------+
```

### keywords
SUBSTRING