SQL：TRIM()函数去除字符串头尾空格

语法

TRIM ( [ LEADING | TRAILING | BOTH ] [characters FROM ] string )
Or
TRIM ( [ characters FROM ] string )
Or
TRIM ( string )

参数说明

• BOTH - 它从字符串的起始和结束位置删除指定的字符（默认位置行为）。
• LEADING - 它从字符串的起始位置删除指定的字符。
• TRAILING - 它从字符串的结束位置删除指定的字符。

移除空格

-- 移除两侧空格
mysql> select trim(' hello ');
+-----------------+
| trim(' hello ') |
+-----------------+
| hello           |
+-----------------+
1 row in set (0.00 sec)

-- 移除开头空格
mysql> select ltrim(' hello ');
+------------------+
| ltrim(' hello ') |
+------------------+
| hello            |
+------------------+
1 row in set (0.01 sec)

-- 移除结尾空格
mysql> select rtrim(' hello ');
+------------------+
| rtrim(' hello ') |
+------------------+
|  hello           |
+------------------+
1 row in set (0.00 sec)

移除指定字符

-- 移除两侧指定字符
mysql> select trim('.' from '.hello.world.');
+--------------------------------+
| trim('.' from '.hello.world.') |
+--------------------------------+
| hello.world                    |
+--------------------------------+
1 row in set (0.00 sec)

-- 等价于
mysql> select trim(both '.' from '.hello.world.');
+-------------------------------------+
| trim(both '.' from '.hello.world.') |
+-------------------------------------+
| hello.world                         |
+-------------------------------------+
1 row in set (0.01 sec)


-- 移除开头指定字符
mysql> select trim(leading '.' from '.hello.world.');
+----------------------------------------+
| trim(leading '.' from '.hello.world.') |
+----------------------------------------+
| hello.world.                           |
+----------------------------------------+
1 row in set (0.01 sec)


-- 移除结尾指定字符
mysql> select trim(trailing '.' from '.hello.world.');
+-----------------------------------------+
| trim(trailing '.' from '.hello.world.') |
+-----------------------------------------+
| .hello.world                            |
+-----------------------------------------+
1 row in set (0.01 sec)

参考

• SQL TRIM()函数去除字符串头尾空格
• SQL TRIM()函数