# **TRIM()**

## **Function Description**

The `TRIM()` function returns a string that deletes unwanted characters.

You can explicitly indicate that the `TRIM()` function is removed from the string by using the `LEADING`, `TRAILING` or `BOTH` options.

If you do not specify anything, the `TRIM()` function uses the `BOTH` option by default.

`[remstr]` is the string to be deleted. The default is a space. That is, if a specific string is not specified, the `TRIM()` function only removes spaces.

## **Function Syntax**

```text
> TRIM([{BOTH | LEADING | TRAILING} [remstr] FROM] str), TRIM([remstr FROM] str)
```

## **Parameter definition**

| Parameters | Description |
| ---- | ---- |
| str | Required parameters. It is to delete the sub-character `remstr` string. |

## **Example**

```text
mysql> select trim(' abc '), trim('abc '), trim('abc'), trim('abc');
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| trim(abc ) | trim(abc ) | trim(abc) | trim(abc) |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| abc | abc | abc | abc |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1 row in set (0.00 sec)

drop table if exists t1;
create table t1(a varchar(100), b varchar(100));
insert into t1 values('abc', 'abc');
insert into t1 values('ah abc', 'ah abc');
insert into t1 values('aaao', 'o');
insert into t1 values('aaao', 'aa');
insert into t1 values('aaao', 'oaa');
mysql> select trim(both a from b) from t1;
+--------------------------+
| trim(both a from b) |
+--------------------------+
| |
| |
| o |
| Ah |
| o Ah |
+--------------------------+
5 rows in set (0.00 sec)

mysql> select trim(leading a from b) from t1;
+-----------------------------+
| trim(leading a from b) |
+-----------------------------+
| |
| |
| o |
| Ah |
| o Ah |
+-----------------------------+
5 rows in set (0.01 sec)

mysql> select trim(trailing a from b) from t1;
+------------------------------+
| trim(trailing a from b) |
+------------------------------+
| |
| |
| o |
| Ah |
| o Ah |
+------------------------------+
5 rows in set (0.00 sec)
```