Question

我有两个问题

SELECT course,
COUNT(*) AS countp 
FROM table1 
WHERE pickout='Yes' 
GROUP BY course

SELECT course,
COUNT(*) AS countw
FROM table1
WHERE pickout='Yes' AND result='Won'
GROUP BY course

我想要实现的是一个包含三列Course，Countp，Countw的表格，但我无法将这两个列合并为一个查询。

基本上我正在寻找一个包含选秀权数量和胜利数量的课程列表。

Answer 1

在MySQL中，条件的结果评估为1或0。你可以总结一下

SELECT course, 
       sum(pickout='Yes') AS countp,
       sum(pickout='Yes' AND result='Won') AS countw
FROM table1 
GROUP BY course

Answer 2

尝试以下SQL：

SELECT 
Course,
COUNT(*) AS CountP,
SUM(CASE WHEN result='Won' THEN 1 ELSE 0 END) AS CountW
FROM table1
WHERE pickout = 'Yes'
GROUP BY Course

Answer 3

试试这个：

select a.course,a.countp ,b.countw  from (SELECT course, COUNT(*) AS countp FROM table1 WHERE pickout='Yes' GROUP BY course)a full join 
(SELECT course, COUNT(*) AS countw FROM table1 WHERE pickout='Yes' AND result='Won' GROUP BY course)b
a.course=b.course

将两个Count Queries组合成一个

3 个答案: