如何修改此查詢？

我有數據庫表重要的列是這樣的：如何修改此查詢？

name | violation 
file1| major 
file1| major 
file1| minor 
file2| minor 
file2| minor

我想結果是這樣的：

name | minor | major etc. 
file1| 1  | 2 
file2| 2  | 0

我已經完成，與此查詢：

select distinct component as cmp ,project_id, 
(select count(severity) from issue_lines where severity = 'MINOR' AND component = cmp) as minor, 
(select count(severity) from issue_lines where severity = 'MAJOR' AND component = cmp) as major, 
(select count(severity) from issue_lines where severity = 'CRITICAL' AND component = cmp) as critical, 
(select count(severity) from issue_lines where severity = 'INFO' AND component = cmp) as info, 
(select count(severity) from issue_lines where severity = 'BLOCKER' AND component = cmp) as blocker 
from issue_lines

現在我想讓它看到，因爲它會被重用很多。但厚顏無恥的ActiveRecord execute（）命令將cmp從子查詢解析到組件中，最後我得到組件==組件，並且它在所有文件中返回完全違規，而不是單個文件。

我可以創建這個視圖沒有問題直接通過工作臺，但這不是一個選項。

是否有可能重寫我的查詢以避免與execute（）命令衝突？

來源

2015-10-20 Tintor

你可以使用別名..或只是重寫查詢情況下，通過報表和組..或轉動 – JamieD77

嗯，這就是問題所在，ActiveRecord的解決別名，打破查詢。你能提供案例使用的例子嗎？它可以在任何數據庫系統上工作嗎？ – Tintor

我的意思是表別名..不列... ..選擇不同的il1.component作爲cmp，il1.project_id，（select count（il2.severity）from issue_lines as il2 where il2.severity ='MINOR'AND il2.component = il1 .component）from issue_lines as il1' – JamieD77

使用上面的示例數據，您可以使用下面的方法重寫您的查詢。

SELECT v.name, 
     COUNT(CASE WHEN v.violation = 'minor' THEN 1 END) as minor, 
     COUNT(CASE WHEN v.violation = 'major' THEN 1 END) as major 
FROM violations as v 
GROUP BY v.name;

SQL Fiddle

來源

2015-10-20 15:48:06 JamieD77

相反子查詢，你可以使用CASE WHEN。

SELECT name, 
     SUM(CASE WHEN v.violation = 'minor' THEN 1 ELSE 0 END) as minor, 
     SUM(CASE WHEN v.violation = 'major' THEN 1 ELSE 0 END) as major 
    FROM violations 
    GROUP BY name;

希望這有助於..

來源

2015-10-20 16:43:34

如何修改此查詢？

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