LOCATE()

locate(substr,str) 查找substr在str中第一次出现的位置，为空时返回0

SELECT login_name, LOCATE('ning',login_name) FROM user WHERE `login_name` ='liangningning';

 locate(substr,str,len)查找substr在str中第len位之后出现的位置，没有显示0

SELECT login_name, LOCATE('ning',login_name,7) FROM user WHERE `login_name` ='liangningning';