跨多個規范化表的 SQL 查詢設計

Question

表關系圖：

基本查詢是：

SELECT DateTime, SubgroupID, TestID 
FROM Subgroups 
WHERE CharID IN (SELECT CharID FROM CharList WHERE ChartType = 2) AND PtLoc > 0

然后我將遍歷記錄集以獲取其他信息：

SELECT DefectDescription, Value 
FROM DefectDescriptions, DataValues 
WHERE SubgroupID = (SubgroupID from above) AND DefectID = SampleNumber 

對於上面的每條記錄：

SELECT TextValue AS PartNum 
FROM ParameterEntries 
WHERE 
    TestID = (TestID from above) 
    AND ParameterID = (SELECT ParameterID FROM ParameterDefinitions WHERE ParameterName = "PartNum")

SELECT TextValue AS SerialNum  
FROM ParameterEntries 
WHERE 
    TestID = (TestID from above) 
    AND ParameterID = (SELECT ParameterID FROM ParameterDefinitions WHERE ParameterName = "SerialNum")

要構建表：

DateTime, PartNum, SerialNum, DefectDescription, Value(number of defects)

這可以在單個查詢中完成，而不是遍歷每條記錄以從鏈接表中獲取記錄嗎？

Answer 1

如果您加入表，您可以將其作為一個查詢進行

SELECT
    Subgroups.DateTime, DefectDescriptions.DefectDescription, DataValues.Value,
    Subgroups.TestID, Count(*) AS NumberOfDefects,
    MAX((SELECT MAX(E.TextValue)
           FROM ParameterDefinitions AS D
           INNER JOIN ParameterEntries AS E ON D.ParameterID = E.ParameterID
           WHERE D.ParameterName="PartNum" AND E.TestID=Subgroups.TestID)
          ) AS PartNum,
    MAX((SELECT MAX(E.TextValue)
           FROM ParameterDefinitions AS D
           INNER JOIN ParameterEntries AS E ON D.ParameterID = E.ParameterID
           WHERE D.ParameterName="SerialNum" AND E.TestID=Subgroups.TestID)
          ) AS SerialNum
FROM
    DefectDescriptions
    INNER JOIN DataValues
        ON DefectDescriptions.DefectID = DataValues.SampleNumber
    INNER JOIN Subgroups
        ON DataValues.SubgroupID = Subgroups.SubgroupID
    INNER JOIN CharList
        ON CharList.CharID = Subgroups.CharID
WHERE
    CharList.CharType=2 AND Subgroups.PtLoc>0
GROUP BY
    Subgroups.DateTime, DefectDescriptions.DefectDescription,
    DataValues.Value, Subgroups.TestID;

如果您將此作為 SQL（在 SQL 視圖中）復制/粘貼到查詢設計器中，您將看到在切換回設計視圖時表是如何連接的。 這兩個參數是通過子查詢選擇的。

您還必須使用 GROUP BY 子句才能使用Count(*)缺陷Count(*)

也可以看看：

• SQL 連接 (w3schools)
• SQL GROUP BY 語句 (w3schools)
• 子查詢 (SQL Server)