select char_length('我们love'); select *, char_length(sname) '姓名字数' from tbl_student; select '对方' + '5'; select '学号:S10013,姓名:' select CONCAT('学号:', sno, ',姓名:', sname) '学生西宁' from tbl_student; select insert('hello,jzp,hi',1, 0, 'dd'); select REPLACE('