SQL返回重复结果

Question

为什么以下SQL查询返回重复的结果？我只想在我的结果集中返回3行。我猜我的加入不正确。约束应从查询联接中得到解释。如果您需要其他信息，请询问。

SELECT 
    [addresstype].name As [Type], 
    [address].city As [City], address.statecode As [State], 
    [address].postalcode As [Zip], 
    [address].addressid As [Id] 
FROM  
    [address]
    LEFT OUTER JOIN [contact_address] ON [address].addressid = [contact_address].addressid 
    LEFT OUTER JOIN [addresstype] ON [addresstype].addresstypeid = [contact_address].addresstypeid 
    LEFT OUTER JOIN [clientcontact] ON dbo.contact_address.contactid = [clientcontact].contactid 
WHERE  
    [contact_address].contactid = 12538 
ORDER BY 
    [address].name, [address].statecode, [address].city  

结果:

======================

更多信息

看来我有多个客户。我具有此联接的原因不是针对此查询，而是针对依赖此查询的另一个查询。它是在.NET代码的自定义规则引擎中构建的。另一个查询需要此clientcontact联接，因为有一个根据UNION查询建立的临时表。如果是这样的话，我真的不需要带有该联接的表(clientcontact)。我得到多行，因为在clientcontact表中有多个clientid。换句话说，这种联系方式对所有这些客户都有效。但是，我想放一个WHERE子句，这样我得到3行，但是我不能弄乱JOINS。根据我上面的解释，这些内容是共享的。如何才能做到这一点？ ...原谅我的正确加入..不应该改变任何事情。不要让那让您感到困惑。 :-)

新查询显示以下内容:

SELECT 
    dbo.clientcontact.clientcontactid ,
    dbo.clientcontact.clientid ,
    dbo.clientcontact.contactid
    --[addresstype].name As [Type], 
    --[address].city As [City], address.statecode As [State], 
    --[address].postalcode As [Zip], 
    --[address].addressid As [Id] 
FROM  
    [address]
    LEFT OUTER JOIN [contact_address] ON [address].addressid = [contact_address].addressid 
    LEFT OUTER JOIN [addresstype] ON [addresstype].addresstypeid = [contact_address].addresstypeid 
    right JOIN [clientcontact] ON dbo.contact_address.contactid = [clientcontact].contactid 
WHERE  
    [contact_address].contactid = 12538 
ORDER BY 
    [address].name, [address].statecode, [address].city  

=================

更多更新

对于为什么我无法删除clientcontact联接，有些人感到困惑。这是因为.NET规则引擎中的另一个查询正在使用相同的查询。请参阅下面的UNION查询的第二个查询。如果绝对没有办法通过保持连接来从中获得3行，那么我猜就是答案。然后，我需要将两者分开。

SELECT 
    client_addressexternal.address_table_type As [Address Record Type], 
    addresstype.name As [Type], 
    CASE WHEN client_addressexternal.address_table_type = 'CLIENT Address' THEN '<a href="/ClientServices/ManageClients/ClientDetails/ClientAddresses.aspx?Id=' + CONVERT(VARCHAR,client_addressexternal.addressid) + '&ClientId=' + CONVERT(VARCHAR,client_addressexternal.client_id) + '&SourceClientId=14103">' + address.name + '</a>' + '<br /><b>Client Name:</b> ' + client_addressexternal.client_full_name ELSE client_addressexternal.contact_full_name END As [Address Name], 
    dbo.limssubstring(dbo.LIMSNullString(address1) + '<br />' + dbo.LIMSNullString(address2), 84) As [Address], 
    address.city As [City], address.statecode As [State], 
    address.postalcode As [Zip], 
    CASE client.clientid WHEN 14103 THEN '' ELSE client.name END As [From Parent Client], 
    address.addressid As [Id] 
FROM  
address 
    JOIN (

        SELECT client_address.clientid, client_address.addressid, client_address.addresstypeid, depth, 'CLIENT Address' AS 'address_table_type', '' as 'contact_full_name', client.name as 'client_full_name', client_address.clientid as 'client_id', '' as 'contact_id'
        FROM dbo.fnClientRelatives(14103, 0, 1, 0) relatives
        inner join client_address on client_address.clientid = relatives.clientid
        LEFT OUTER JOIN client ON relatives.clientid = dbo.client.clientid

        UNION

        SELECT clientcontact.clientid, contact_address.addressid, contact_address.addresstypeid, 999 [depth], 'CONTACT Address' AS 'address_table_type', address.name + '<br /><b>Contact Name:</b> ' + LTRIM(RTRIM(ISNULL(contact.firstname, '') + ISNULL(' ' + contact.middleinitial + ' ', ' ') + ISNULL(contact.lastname, ''))), '' as 'client_full_name', clientcontact.clientid as 'client_id', clientcontact.contactid as 'contact_id'
        from clientcontact 
        inner join contact_address ON contact_address.contactid=clientcontact.contactid and clientcontact.clientid=14103
        LEFT OUTER JOIN [contact] ON [clientcontact].contactid = [contact].contactid
        LEFT OUTER JOIN [address] ON contact_address.addressid = address.addressid

    ) AS client_addressexternal ON client_addressexternal.addressid = address.addressid 
    JOIN client ON client.clientid = client_addressexternal.clientid 
    JOIN addresstype on addresstype.addresstypeid = client_addressexternal.addresstypeid 
 ORDER BY 
    depth,address.statecode, address.city, address.name     

如果您对此 super 感兴趣，请使用以下函数:

GO
/****** Object:  UserDefinedFunction [dbo].[fnClientRelatives]    Script Date: 07/29/2011 12:48:24 ******/
SET ANSI_NULLS OFF
GO
SET QUOTED_IDENTIFIER ON
GO
--your basic recursive tree searcher.
--childrennotparents = 1 means you'll get children. = 0 means you'll get parents
--@recursive = 1 means it finds all children, grandchildren, etc... or whatever
-- The depth is the base level to start incrementing each level, if set to zero, the @clientid will also be part of the results
ALTER  FUNCTION [dbo].[fnClientRelatives]
(
    @clientId INT,
    @childrenNotParents BIT,
    @recursive bit,
    @depth int
)
RETURNS @clientids TABLE (clientid INT primary key clustered, depth int)
AS
begin

-- Add the parent client id if the depth is zero
if @depth = 0
begin
    INSERT INTO @clientids VALUES (@clientid, @depth)
end
set @depth = @depth + 1

IF @childrenNotParents = 1  
begin
    DECLARE clientids CURSOR FOR  
        SELECT clientid
        FROM client
        where parentclientid = @clientId
END--/if childrennotparents
ELSE--if not childrennotparents  
BEGIN  
    DECLARE clientids CURSOR FOR  
        SELECT parentclientid
        FROM client
        where clientid = @clientid
END--/if not childrennotparents

OPEN clientids
DECLARE @nextClientID INT
FETCH clientids INTO @nextClientID
--@nextClientID may be null if we're loading parents, and the
--current client has null for a parent id.
WHILE @@FETCH_STATUS = 0 AND @nextClientID IS NOT NULL
BEGIN  
    INSERT INTO @clientids
    VALUES (@nextclientid, @depth)

    IF @recursive = 1  
    BEGIN  
        INSERT INTO @clientids  
            SELECT * FROM dbo.fnClientRelatives(@nextclientid, @childrenNotParents, @recursive, @depth)    
    END--IF @recursive = 1    
FETCH clientids INTO @nextclientid  
END--WHILE @@FETCH_STATUS = 0  

CLOSE clientids  
DEALLOCATE clientids  

RETURN   
END--/IssueRelatives

地址的数据库图:

Answer 1

理解为什么从查询中获得多个重复行是学习SQL的一项关键技能-这是我建议使用SELECT *而不是使用列列表的少数几个地方之一。

一旦查看了整个(宽)结果集，就可以希望确定整个结果集包含差异的位置(即使仅包含5列的投影结果集看起来是相同的)。仅通过检查这些差异，您就可以确定如何更新原始查询:-通过将条件添加到WHERE子句，将条件添加到ON的JOIN子句之一，或引入可以减少结果集的新JOIN 。