Question

我所拥有的是由于外部列而返回两行的联合查询。它在上半部分返回一行''，就像它的假设一样，在下半部分返回在连接中找到的实际字段。如果连接中没有任何内容，我基本上需要有''行。我理解联盟的性质重复数据删除，我理解为什么这不是重复数据删除，但我不知道如何得到它所以我只有连接中的行有一个''。

SELECT Me, Ope, Dd,U11, Id3, Legal
       , PAI = (SELECT tbluser.user FROM tbluser WHERE tblmat.PAI = tbluser.userid)
       , Ial = (SELECT tbluser.user FROM tbluser WHERE tblmat.Id3 = tbluser.userid)
       , '' AS Outside, Dagal
FROM tblmat
WHERE MStatus = 'Open'
    AND (mgroup = 'Cas' OR templategroup = 'Sub' OR tmattertemplate = 'Ss')
    AND (Opte <= CONVERT (NCHAR (8), GETDATE (), 112)
    AND Opte >= DateADD (mm, -6, GETDATE ()))
    AND lookup2 IN('NOL','NH','NE')
UNION
SELECT Me, Ope, Dd, U11, Id3, Legal
       , PAI = (SELECT tbluser.user FROM tbluser WHERE tblmat.PAI = tbluser.userid)
       , Ial = (SELECT tbluser.user FROM tbluser WHERE tblmat.Id3 = tbluser.userid)
       , tblCon.ContactName AS Outside, Dagal
FROM    ttblmat
JOIN tblMatRelatedItems ON tblmat.me = tblMatRelatedItems.me
JOIN tblcon ON tblMatRelatedItems.relatedkey = tblcon.contactid
WHERE MStatus = 'Open'
    AND (mgroup = 'Cas' OR templategroup = 'Sub' OR tmattertemplate = 'Ss')
    AND (Opte <= CONVERT (NCHAR (8), GETDATE (), 112)
    AND Opte >= DateADD (mm, -6, GETDATE ()))
    AND lookup2 IN('NOL','NH','NE') 
    AND tblmatterRelateditems.RelatedItem = 'Contact'
    AND tblcontacts.contacttype = 'Managing Partner'

Answer 1

您可以尝试围绕另一个查询包装整个事物。您没有指定数据库，但语法如下所示：

SELECT    Me, Ope, Dd, U11, Id3, Legal, PAI, Ial, MAX(Outside), Dagal FROM
( your current UNION query)
GROUP BY Me, Ope, Dd, U11, Id3, Legal, PAI, Ial, Dagal

Answer 2

尝试使用join 这会有所帮助如果两个表中的条件不匹配，则内连接不会给出结果

Answer 3

你试过看COALESCE算子吗？

http://msdn.microsoft.com/en-us/library/ms190349.aspx

您的示例可能看起来像这样（完全未经测试，可能无法返回正确的结果。这是一个指导原则）：

SELECT Me, Ope, Dd, U11, Id3, Legal
   , PAI = (SELECT tbluser.user FROM tbluser WHERE tblmat.PAI = tbluser.userid)
   , Ial = (SELECT tbluser.user FROM tbluser WHERE tblmat.Id3 = tbluser.userid)
   , COALESCE(tblCon.ContactName, '') AS Outside, Dagal
FROM    ttblmat
JOIN tblMatRelatedItems ON tblmat.me = tblMatRelatedItems.me
JOIN tblcon ON tblMatRelatedItems.relatedkey = tblcon.contactid
WHERE MStatus = 'Open'
AND (mgroup = 'Cas' OR templategroup = 'Sub' OR tmattertemplate = 'Ss')
AND (Opte <= CONVERT (NCHAR (8), GETDATE (), 112)
AND Opte >= DateADD (mm, -6, GETDATE ()))
AND lookup2 IN('NOL','NH','NE') 
AND tblmatterRelateditems.RelatedItem = 'Contact'
   AND tblcontacts.contacttype = 'Managing Partner'

Answer 4

您可以使用单个左外连接，并在 on 子句中为您提供连接约束，以完成您的任务

SELECT
    Me,
    Ope,
    Dd,
    U11,
    Id3,
    Legal,
    PAI = (SELECT tbluser.user FROM tbluser WHERE tblmat.PAI = tbluser.userid),
    Ial = (SELECT tbluser.user FROM tbluser WHERE tblmat.Id3 = tbluser.userid),
    isnull(tblCon.ContactName,'') AS Outside,
    Dagal
FROM
    ttblmat
LEFT OUTER JOIN
    tblMatRelatedItems
ON
    tblmat.me = tblMatRelatedItems.me and
    tblmatterRelateditems.RelatedItem = 'Contact'
LEFT OUTER JOIN
    tblcon
ON
    tblMatRelatedItems.relatedkey = tblcon.contactid and
    tblcon.contacttype = 'Managing Partner' 
WHERE
    MStatus = 'Open' AND
    (mgroup = 'Cas' OR templategroup = 'Sub' OR tmattertemplate = 'Ss') AND
    (Opte <= CONVERT (NCHAR (8), GETDATE (), 112) AND
    Opte >= DateADD (mm, -6, GETDATE ())) AND
    lookup2 IN('NOL','NH','NE')

SQL查询从union复制行

4 个答案: