mysql中功能强大的trim()函数.
去除两边空格：
mysql> select trim(' hello world '); +-----------------------+ | trim(' hello world ') | +-----------------------+ | hello world | +-----------------------+ 1 row in set
去除左边空格：
select ltrim(' hello world ');
去除右边空格：
select rtrim(' hello world ');
trim函数还可以过滤指定字符串：
去除两边逗号：
mysql> SELECT TRIM(BOTH ',' FROM ',a,b,c,'); +-------------------------------+ | TRIM(BOTH ',' FROM ',a,b,c,') | +-------------------------------+ | a,b,c | +-------------------------------+ 1 row in set
去除左边逗号：
mysql> SELECT TRIM(LEADING ',' FROM ',,,abc'); +---------------------------------+ | TRIM(LEADING ',' FROM ',,,abc') | +---------------------------------+ | abc | +---------------------------------+ 1 row in set
去除右边逗号：
mysql> SELECT TRIM(TRAILING ',' FROM ',,,abc,,,,,'); +---------------------------------------+ | TRIM(TRAILING ',' FROM ',,,abc,,,,,') | +---------------------------------------+ | ,,,abc | +---------------------------------------+ 1 row in set