Question

确定，

我有一个表发布，它有PublicationID，PublisherID，NameAbbrev ...并且它连接到另一个名为AreaBuy的表，它有一个AreaBuyID字段，NameAbbrev，DateCreated和CreatedBy字段。这种关系基本上是公司为我们的产品签署了一组论文（不一定由同一家伞公司拥有）。发布和AreaBuy表是通过PublicationAreaBuy表连接的，该表具有1 ... M ... 1的关系（巧妙的名称对！）。

我的问题是：我想从发布表中选择一组出版物，假设我们在今年第一天到现在之间签署了这些出版物，但如果返回的任何论文都在AreaBuy组中，我想要的也回来了！踢球者，我只想返回两列，这将是所有发布ID和名称，所以我希望AreaBuy信息包含在这两列中。所以我要说我在我的集合中得到五个结果：

idNum | name
1       The Herald
2       L A Times  
162     L A Area Buy
230     County Enquirer
2006    Illinois Post

所以，LA时代是在洛杉矶地区购买，所以也出现了 - 你是怎么做到的？将一组结果信息合并到另一组中？

对不起，这是一个糟糕的解释，R。

Answer 1

好的，我想我会按照您的需要进行操作。我觉得这样的事情可以解决问题。

SELECT Publication.PublicationID, Publication.NameAbbrev
FROM Publication
UNION ALL
SELECT AreaBuy.AreaBuyID, AreaBuy.NameAbbrev
FROM AreaBuy
INNER JOIN PublicationAreaBuy
ON AreaBuy.AreaBuyID = PublicationAreaBuy.AreaBuyID
INNER JOIN Publication
ON PublicationAreaBuy.PublicationID = Publication.PublicationID

根据需要添加DateCreated的钩子或任何其他判别。

Answer 2

很难说，解释不太清楚，但你肯定想要使用连接。从阅读你的问题来看，这是我能得到的最接近你想要的东西。

SELECT P.PublicationID, P.Name
From Publication P
LEFT JOIN PublicationAreaBuy AS PAB
ON P.PublicationID = PAB.PublicationID
LEFT JOIN AreaBuy AS AB 
ON PAB.AreaBuyID = AB.AreaBuyID
WHERE P.SignedUp > @firstDayOfYear
OR Not AB.AreaBuyID is NULL

这将返回在一年的第一天之后注册的所有发布的PublicationID和发布名称，或者它们是否在PublicationAreaBuy表中。

Answer 3

这实际上是一个支点，但它最容易表示为两个不同集合的UNION - 出版物集和它们所链接的区域集。正常的UNION去除了集合，所以通常会慢一点。 UNION ALL可能会产生多个区域，因为两个出版物位于同一区域，因此如果您使用DISTINCT，则需要UNION ALL来停止重复项：

SELECT 'Publication' AS RowType
    ,Publication.PublicationID AS idNum
    ,Publication.NameAbbrev AS name
FROM Publication
WHERE Publication.SignedUp >= '1/1/2009'

UNION ALL

SELECT DISTINCT 'Area' AS RowType
    ,AreaBuy.AreaBuyID AS idNum
    ,AreaBuy.NameAbbrev AS name
FROM AreaBuy
INNER JOIN PublicationAreaBuy
    ON AreaBuy.AreaBuyID = PublicationAreaBuy.AreaBuyID
INNER JOIN Publication
    ON PublicationAreaBuy.PublicationID = Publication.PublicationID
WHERE Publication.SignedUp >= '1/1/2009'

或使用UNION：

SELECT 'Publication' AS RowType
    ,Publication.PublicationID AS idNum
    ,Publication.NameAbbrev AS name
FROM Publication
WHERE Publication.SignedUp >= '1/1/2009'

UNION

SELECT 'Area' AS RowType
    ,AreaBuy.AreaBuyID AS idNum
    ,AreaBuy.NameAbbrev AS name
FROM AreaBuy
INNER JOIN PublicationAreaBuy
    ON AreaBuy.AreaBuyID = PublicationAreaBuy.AreaBuyID
INNER JOIN Publication
    ON PublicationAreaBuy.PublicationID = Publication.PublicationID
WHERE Publication.SignedUp >= '1/1/2009'

在支持公用表表达式的SQL方言中，您可以通过执行以下操作来避免重复更复杂的业务逻辑：

WITH SelectedPubs AS (
    SELECT Publication.PublicationID
        ,Publication.NameAbbrev
    FROM Publication
    WHERE Publication.SignedUp >= '1/1/2009'
)
SELECT 'Publication' AS RowType
        , SelectedPubs.PublicationID AS idNum
        ,SelectedPubs.NameAbbrev AS name
FROM SelectedPubs

UNION

SELECT 'Area' AS RowType
    ,AreaBuy.AreaBuyID AS idNum
    ,AreaBuy.NameAbbrev AS name
FROM AreaBuy
INNER JOIN PublicationAreaBuy
    ON AreaBuy.AreaBuyID = PublicationAreaBuy.AreaBuyID
INNER JOIN SelectedPubs
    ON PublicationAreaBuy.PublicationID = SelectedPubs.PublicationID

SQL在返回的行中添加行

3 个答案: