SQL Case when 的使用方法

统计每个职业 男女 每个等级 各有多少SELECT CASE roleType WHEN 1 THEN '战士'WHEN 2 THEN '法师'WHEN 3 THEN '潜伏者'WHEN 4 THEN '大祭司'WHEN 5 THEN '弓箭手'END AS role,CASE sex WHEN 0 THEN '女'WHEN 1 THEN '男'END AS sexb,LEVEL,COUNT(1) count1FROM t_playerGROUP BY role,sexb,LEVELORDER BY role,sexb,LEVEL--简单Case函数CASE sexWHEN '1' THEN '男'WHEN '2' THEN '女'ELSE '其他' END--Case搜索函数CASE WHEN sex = '1' THEN '男'WHEN sex = '2' THEN '女'ELSE '其他' END也可以用这个方法来判断工资的等级，并统计每一等级的人数。SQL代码如下；

SELECT
CASE WHEN salary <= 500 THEN '1'
WHEN salary > 500 AND salary <= 600  THEN '2'
WHEN salary > 600 AND salary <= 800  THEN '3'
WHEN salary > 800 AND salary <= 1000 THEN '4'
ELSE NULL END salary_class,
COUNT(*)
FROM    Table_A
GROUP BY
CASE WHEN salary <= 500 THEN '1'
WHEN salary > 500 AND salary <= 600  THEN '2'
WHEN salary > 600 AND salary <= 800  THEN '3'
WHEN salary > 800 AND salary <= 1000 THEN '4'
ELSE NULL END;