Question

我有两个专栏＆＃39; Team＆＃39;和＆＃39; WLD＆＃39;在mysql数据库中。 WLD代表Won，Lost，Drawn，并且每行数百包含W，L或D.我想输出一个SELECT中列中有多少W，L和D。

如果我用其中一个做到这一点就可以了：

SELECT Team, COUNT(WLA) AS Won FROM ResultsTest WHERE WLA = 'W'

然而，只要我添加另一个COUNT语句，它就会开始抱怨：

SELECT Team, COUNT(WLA) AS Won 
FROM ResultsTest 
WHERE WLA = 'W', 
COUNT(WLA) AS Lost FROM ResultsTest WHERE WLA = 'L'

我哪里错了？

Answer 1

您需要GROUP BY子句才能完成数据聚合。最重要的是，如果您不想为胜负创建两个不同的提取并加入它们，您可以在以下情况下使用二进制和：

SELECT Team,
       COUNT(*) AS Matches,
       SUM(CASE WHEN WLD = 'W' THEN 1 ELSE 0 END) AS Wins,
       SUM(CASE WHEN WLD = 'L' THEN 1 ELSE 0 END) AS Losses,
       SUM(CASE WHEN WLD != 'W' AND WLD != 'L' THEN 1 ELSE 0 END) AS Draws
FROM ResultsTest
GROUP BY Team

Answer 2

谢谢你们。有用。节省了我很多时间：

SELECT Team, 
       COUNT(*) WLD, 
       SUM(CASE WHEN WLD = 'W' THEN 1 ELSE 0 END) AS Won, 
       SUM(CASE WHEN WLD = 'L' THEN 1 ELSE 0 END) AS Lost, 
       SUM(CASE WHEN WLD = 'D' THEN 1 ELSE 0 END) AS Drawn 
FROM ResultsTest 
GROUP BY Team

在一个php脚本SELECT查询中对同一列执行多个COUNT

2 个答案: