從JOIN算起的行數

Question

{ 
SELECT tp.ProjectID, tp.ProjectName, tp.ProjectDescription, tp.Developer, 
     tp.Owner, tp.StartDate, tp.CloseDate, tp.ProjectStatus, tp.CompletionPct, 
     Count(tb.ProjectID) as 'NumberofBugs' 
FROM tblBTProject tp 
LEFT JOIN tblBTBugs tb ON tp.ProjectID = tb.ProjectID 
GROUP BY tp.ProjectID, tp.ProjectName, tp.ProjectDescription, tp.Developer, 
     tp.Owner, tp.StartDate, tp.CloseDate, tp.ProjectStatus, tp.CompletionPct 
} 

有沒有更好的方法來寫這個？ 我加入2個表格（tblBTProject tp & tblBTBugs tb）。在有多個專案編號在tblBTBugs TB，並試圖返回多個項目ID的計數的列

感謝

Answer 1

這是如何從tblBTBugs

SELECT COUNT(DISTINCT(ProjectID)) FROM tblBTBugs 

，這是所有不同項目如何讓每一個項目的tblBTBugs

SELECT ProjectID, COUNT(ProjectID) 
FROM tblBTBugs 
GROUP BY ProjectID 

或數字，如果你想所有的列

SELECT * FROM tblBTBugs 
WHERE ProjectID IN (SELECT ProjectID 
        FROM (SELECT ProjectID, COUNT(ProjectID) 
          FROM tblBTBugs 
          GROUP BY ProjectID))