用户根据日期搜索数据

select * from employees where hiredate BETWEEN STR_TO_DATE(‘1998-3‘,‘%Y-%c-%d‘) and STR_TO_DATE(‘1999-2‘,‘%Y-%c-%d‘)

if的常用用法

select last_name,commission_pct, IF( commission_pct is NULL,‘幸苦了‘,‘加油干‘) 备注  from employees 

case when 的常用用法(swicth)

SELECT
    NAME ‘英雄‘,
    CASE NAME
        WHEN ‘德莱文‘ THEN
            ‘斧子‘
        WHEN ‘德玛西亚-盖伦‘ THEN
            ‘大宝剑‘
        WHEN ‘暗夜猎手-VN‘ THEN
            ‘弩‘
        ELSE
            ‘无‘
    END ‘装备‘
FROM
    user_info;

case when 的常用用法(if else if ... else)

SELECT
    NAME ‘英雄‘,
    age ‘年龄‘,
    CASE
        WHEN age < 18 THEN
            ‘少年‘
        WHEN age < 30 THEN
            ‘青年‘
        WHEN age >= 30
        AND age < 50 THEN
            ‘中年‘
        ELSE
            ‘老年‘
    END ‘状态‘
FROM
    user_info;

Mysql 常用小技巧