MS SQL 2008加入 - 从许多结果中选择一个

我试图运行以下查询，但不确定如何将其限制为仅一个结果。在下面的查询中，clientcontactid 21901适用的客户端有2个地址，即2个结果返回。MS SQL 2008加入 - 从许多结果中选择一个

查询：

select cc.contactpersonid, 
    cc.clientcontactid, 
    ad.city, 
    ad.addressid 
from SavedList sl 
inner join ClientContacts cc on cc.ContactPersonId = sl.ObjectId 
inner join Clients c on c.ClientID = cc.ClientId 
inner join Address ad on c.ClientID = ad.ObjectId 
where sl.SavedListId = 2117

结果：

contactpersonid clientcontactid city addressid 
87934   21901     145186 
87934   21901   London 1130705 
89778   17275   Leeds 145368

我需要返回的结果之一客户联系，则优先级为上一个与城市的它。我试过选择顶部（1），但我认为这是由于联合迫使多个记录回来。如何返回只有1结果的任何帮助，以及如何控制，将不胜感激！

感谢

来源

2012-06-20 franglais

尝试：

;WITH a AS (
select cc.contactpersonid, 
    cc.clientcontactid, 
    ad.city, 
    ad.addressid, 
    ROW_NUMBER() OVER (PARTITION BY cc.clientcontactid ORDER BY ad.city DESC) AS RowNum 
    from SavedList sl 
    inner join ClientContacts cc on cc.ContactPersonId = sl.ObjectId 
    inner join Clients c on c.ClientID = cc.ClientId 
    inner join Address ad on c.ClientID = ad.ObjectId 
    where sl.SavedListId = 2117 
) 

SELECT * 
FROM a 
WHERE RowNum = 1

来源

2012-06-20 09:28:45

您可以通过添加条件，其中city is not NULL尝试select top 1 record。

来源

2012-06-20 09:24:33

问题放在哪里城市不是null是否有一些记录将在城市中为null，如果没有其他选择，我很乐意返回这些记录。你会把选择的顶部1放在哪里？如果它进入顶端，那么它将只返回带有clientcontact 21901的顶部行，并且不会返回clientcontact 17275的顶部行！ – franglais

我通常会优先处理结果的做法是实际分配优先级值列。在这种情况下，它可以保持简单，因为只有一个重点：随着城市的记录来到城市之前没有：

with q as(
select cc.contactpersonid, 
    cc.clientcontactid, 
    ad.city, 
    ad.addressid, 
    case when ad.city is null then 0 else 1 end prior 
from SavedList sl 
inner join ClientContacts cc on cc.ContactPersonId = sl.ObjectId 
inner join Clients c on c.ClientID = cc.ClientId 
inner join Address ad on c.ClientID = ad.ObjectId 
where sl.SavedListId = 2117 
) 
select top 1 * from q order by prior desc

来源

2012-06-20 09:26:41

大，但它的工作原理：

select cc.contactpersonid, 
     cc.clientcontactid, 
     ad.city, 
     ad.addressid 
from SavedList sl 
inner join ClientContacts cc on cc.ContactPersonId = sl.ObjectId 
inner join Clients c on c.ClientID = cc.ClientId 
inner join Address ad on c.ClientID = ad.ObjectId 
where sl.SavedListId = 2117 and (ad.city is not null or ad.city <> '') 
UNION 
select cc.contactpersonid, 
     cc.clientcontactid, 
     ad.city, 
     ad.addressid 
from SavedList sl 
inner join ClientContacts cc on cc.ContactPersonId = sl.ObjectId 
inner join Clients c on c.ClientID = cc.ClientId 
inner join Address ad on c.ClientID = ad.ObjectId 
where sl.SavedListId = 2117 and (ad.city is null or ad.city = '') 
and cc.clientcontactid not in (
    select cc.clientcontactid 
    from SavedList sl 
    inner join ClientContacts cc on cc.ContactPersonId = sl.ObjectId 
    inner join Clients c on c.ClientID = cc.ClientId 
    inner join Address ad on c.ClientID = ad.ObjectId 
    where sl.SavedListId = 2117 and (ad.city is not null or ad.city <> '') 
)

来源

2012-06-20 09:27:08

你是对的 - 它很大，但确实有效！只是出于兴趣，** ad.city不是null或ad.city <> ** **和** isnull（ad.city，''）<>'** **之间有任何区别吗？ – franglais

@ sam.clements nop，你可以使用'isnull'代替:) –

试试这个：

;WITH cte 
    AS (SELECT cc.contactpersonid, 
       cc.clientcontactid, 
       ad.city, 
       ad.addressid, 
       Row_number() OVER (PARTITION BY cc.clientcontactid ORDER BY CASE WHEN ad.city <> '' THEN 1 ELSE 0 END) rn 
     FROM SavedList sl 
       INNER JOIN ClientContacts cc 
        ON cc.ContactPersonId = sl.ObjectId 
       INNER JOIN Clients c 
        ON c.ClientID = cc.ClientId 
       INNER JOIN Address ad 
        ON c.ClientID = ad.ObjectId 
     WHERE sl.SavedListId = 2117) 
SELECT contactpersonid, 
     clientcontactid, 
     city, 
     addressid 
FROM cte 
WHERE rn = 1

来源

2012-06-20 09:33:30 Bridge

MS SQL 2008加入 - 从许多结果中选择一个

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