复杂的表连接的SQL

Question

PLS我想根据PressKit表数据从文章表中获取数据

我需要帮助如何文章表和PressKit表

虽然我之间的连接它们之间是不同的中间表？

我想要得到的数据一样，

SELECT ArticleID , 
     ArticaleTile 
FROM Articles 
WHERE dbo.MagazineID IN (
     SELECT dbo.Magazines.MagazineID 
     FROM dbo.Magazines 
       INNER JOIN dbo.PressKitMagazines ON dbo.Magazines.MagazineID = dbo.PressKitMagazines.MagazineID 
     WHERE PressKitID = @PressKitID) 
     AND ClassID IN (
     SELECT Class.classID 
     FROM dbo.Class 
       INNER JOIN dbo.PressKitClass ON Class.classID = PressKitClass.classID 
     WHERE PressKitID = @PressKitID) 

Answer 1

SELECT ArticleID, ArticleTitle 
FROM Articles a 
JOIN dbo.PressKitMagazines pm 
ON a.MagazineID = pm.MagazineID AND pm.PressKitID = @PressKitID 
JOIN dbo.PressKitClass pc 
ON a.ClassID = pc.ClassID AND pc.PressKitID = @PressKitID 

你并不需要涉及Magazines，Class或PressKit因为你并不需要返回与他们ID S相关的Name秒。你并不需要他们在您的原始查询之一：

SELECT ArticleID, ArticleTitle 
FROM Articles 
WHERE MagazineID IN (
    SELECT MagazineID 
    FROM dbo.PressKitMagazines 
    WHERE PressKitID = @PressKitID) 
AND ClassID IN (
    SELECT classID 
    FROM dbo.PressKitClass 
    WHERE PressKitID = @PressKitID) 

假设表T认为，使通过其列参数为一个真正的声明了一些语句行。例如Articles认为，满足行：
        “文章条款ArticleID题为ArticleTitle在杂志MagazineID &是类的CLASSID”
或简写：
       文章（ArticleID，ArticleTitle，MagazineID，ClassID）
在SQL SELECT语句中，表的列名称前缀为别名和点（当没有歧义时可以省略）：
          a（a.ArticleID，a.ArticleTitle，a.MagazineID，a。的ClassID）
所以在行：
        SELECT C FROM U WHERE C IN (SELECT C FROM T WHEREcondition)
或前缀和点数：
        SELECT U.C FROM U WHERE U.C IN (SELECT T.C FROM T WHEREcondition)
都行，其中：
        SELECT U.C FROM U JOIN T ONconditionAND U.C = T.C
，因为它们都返回行只列C，其中：
        U（...，UC，...）和T（...，TC，.. ）和条件 AND UC = TC

对于撰写查询，请参阅this answer。

Answer 2

试试这个。它只是一个INNER JOIN与PressKitID你正在寻找的表，然后简单的WHERE子句可以决定你想要的具体参数：

SELECT 
    a.ArticleID, a.ArticleTitle 
FROM articles AS a 
INNER JOIN PressKitMagazines AS m 
ON a.magazineid = m.magazineid 
INNER JOIN PressKitClass AS c 
ON a.classid = c.classid 
WHERE 
    m.PressKitID = @PressKitID 
    OR 
    c.PressKitID = @PressKitID 

Answer 3

使用在所有情况下左连接尝试。

SELECT Articles.ArticleID , 
     Articles.ArticleTitle 
FROM dbo.Articles 
LEFT JOIN dbo.Magazines ON Magazines.MagID = Articles.MagID 
LEFT JOIN dbo.Class ON Class.ClassID = Articles.ClassID 
LEFT JOIN dbo.PressKitMag ON PressKitMag.MagID = Magazines.MagID 
LEFT JOIN dbo.PressKitClass ON PressKitClass.ClassID = Class.ClassID 
LEFT JOIN dbo.PressKit ON PressKit.PressKitID = PressKitClass.PressKitID AND PressKit.PressKitID = PressKitMag.PressKitID 
WHERE PressKit.PressKitID=@PressKitID 

如果我假设你正在使用“PressKitMagazines”对于许多人“PressKit”和“杂志”之间有很多关系，那么你应该使用一个唯一键列“PressKitMagazines”象下面这样：

Answer 4

目前尚不清楚是什么问题，但是，我建议使用EXISTS，像这样：

SELECT 
     A.ArticleID 
    , A.ArticaleTile 
FROM Articles AS A 
WHERE EXISTS (
      SELECT NULL 
      FROM dbo.Magazines AS M 
        INNER JOIN dbo.PressKitMagazines AS PKM ON M.MagazineID = PKM.MagazineID 
      WHERE M.PressKitID = @PressKitID 
        AND A.ArticleID = M.MagazineID 
    ) 
    OR EXISTS (
      SELECT NULL 
      FROM dbo.Class AS C 
        INNER JOIN dbo.PressKitClass PKK ON C.classID = PKK.classID 
      WHERE C.PressKitID = @PressKitID 
        AND A.ClassID = C.ClassID 
    ) 

我也相信你需要在where子句中的这两个子查询之间使用或。