MySQL中CASE WHEN与COUNT结合进行条件统计1. CASE WHEN语句在MySQL中的基本用法 CASE WHEN语句在MySQL中用于实现条件逻辑,类似于编程语言中的if-else结构。它允许在SELECT、UPDATE、DELETE等SQL语句中根据条件返回不同的结果。CASE WHEN语句的基本语法如下:
insert into test_list values(1,10,'张一',1),(2,15,'张二',2),(3,20,'张三',1),(4,25,'张四',2),(5,30,'张五',1); 简单case函数实例: -- 统计年龄,姓名条件的 select count(case age when 10 then age else null end) as age_num,count(case name when '张五' then name end) ...
方法3:使用CASE WHEN CASE WHEN语句的功能很强大,可以定义灵活的查询条件,很适合进行分类统计。 SQL Query 1. SELECT 2. COUNT( CASE WHEN `mother` >24 THEN 1 ELSE NULL END ) AS `digong`, 3. COUNT( CASE WHEN `mother` <=24 THEN 1 ELSE NULL END ) AS `tiangong` 4. FROM prince 1. 2....
select s.c_id,c_name,count(s_score) as 单科总人数, SUM(case when s_score>=0 and s_score<=60 then 1 else 0 end) as 0_60_人数, SUM(case when s_score>=0 and s_score<=60 then 1 else 0 end)/COUNT(s_id) as 0_60_占比, SUM(case when s_score>60 and s_score<=70 then...
select getdate() as 日期,case month(getdate()) when 11 then '十一' when 12 then '十二'...
SELECT customer_number FROM orders GROUPBY customer_number ORDERBY COUNT(customer_number)DESC LIMIT 1 编写SQL查询以查找每个部门中薪资最高的员工。按任意顺序返回结果表。查询结果格式如下例所示。 输入: Employee 表: +---+---+---+---+ | id | name | salary | department...
不然会导致转换无效. SELECT id, case WHEN cast(`status` AS SIGNED) < 45 THEN '1' WHEN cast...
SELECT COUNT(CASE WHEN column_name = 'value' THEN 1 END) AS count_condition FROM your_table;这个查询的目的是计算在表your_table中满足条件column_name = 'value'的行数。CASE WHEN语句会返回 1 来表示满足条件，然后COUNT函数会统计这些值的数量。你也可以结合多个条件，例如：SELECT COUNT(CASE WHEN ...
select (case when point is null then '不及格' when point>0 and point <60 then '不及格' when point>=60 and point <=80 then '良好' when point>80 and point <=100 then '优秀' else '不及格' end ) as pointv,count(1) count ...