不等于

SQL中表示不等于有两种方式:

  1. <>
  2. !=

CASE WHEN

case when类似于编程语言中的switch语法,通常用在select语句中确定最终的值,如下:

SELECT userid, name, school, (case sex when male then '男' when female then '女' else "保密" end) as sex FROM user;