合并多个查询答案

【问题标题】：Combine multiple query合并多个查询
【发布时间】：2014-07-03 14:26:43
【问题描述】：

我正在以下查询获取考试状态是否失败、暂停和通过。页面上还有其他查询，因此我的页面有很多时间来加载。我已经优化了其他查询。

如何结合这些查询来快速获得结果？可能所有这些查询都可以使用“CASE WHEN”进行组合，有人可以帮我优化下面的查询吗？

SELECT  COUNT(*) AS countFailMT FROM questionPaper WHERE subjectTopic like 'MT%' result=0)
SELECT  COUNT(*) AS countPauseMT FROM questionPaper WHERE subjectTopic like 'MT%' result=-1)
SELECT  COUNT(*) AS countPassMT FROM questionPaper WHERE subjectTopic like 'MT%' result>=1)

SELECT  COUNT(*) AS countFailEN FROM questionPaper WHERE subjectTopic like 'EN%' result=0)
SELECT  COUNT(*) AS countPauseEN FROM questionPaper WHERE subjectTopic like 'EN%' result=-1)
SELECT  COUNT(*) AS countPassEN FROM questionPaper WHERE subjectTopic like 'EN%' result>=1)

【问题讨论】：

来吧。尝试一下
您的where 条件缺少and。
或者不要尝试任何事情，只是放松一下，让我们为您完成所有工作。

标签： mysql sql database count case

【解决方案1】：

您想使用条件聚合。这在 MySQL 中很容易：

select sum(subjectTopic like 'MT%' and result=0) as countFailMT,
       sum(subjectTopic like 'MT%' and result=-1) as countPauseMT,
       sum(subjectTopic like 'MT%' and result>=1) as countPassMT,
       sum(subjectTopic like 'EN%' and result=0) as countFailEN,
       sum(subjectTopic like 'EN%' and result=-1) as countPauseEN,
       sum(subjectTopic like 'EN%' and result>=1) as countPassEN
from questionPaper;

我假设where 子句中的条件由AND 连接，在创建问题时不知何故丢失了。

【讨论】：