1

我有一个人表，另一个联系人类型（电子邮件、电话等）和一个连接表来保存联系人。

我想构建一个查询来获取一条记录中每个人的电子邮件、电话、邮政信箱，

所以我将有 4 列结果集 UserName、Tel、Email、PO

当我使用 SQL Server 2000 时，XML 不是一个选项。

任何帮助使其工作的帮助将不胜感激。

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3 回答 3

1

您未能提供有关列的任何有用详细信息，因此我不得不猜测，但我认为您正在寻找类似的东西。

WITH Persons(PersonId, UserName) AS
(
SELECT 1, 'Bob' UNION ALL
SELECT 2, 'Bill'
), ContactTypes(ContactTypeId, Name) AS
(
SELECT 1, 'Tel' UNION ALL
SELECT 2, 'Email' UNION ALL
SELECT 3, 'PO'
),PersonContacts(PersonId, ContactTypeId, Value) As
(
SELECT 1,1,CAST('(01223) 123456' AS VARCHAR(50)) UNION ALL
SELECT 1,2,CAST('bob@example.com' AS VARCHAR(50)) UNION ALL
SELECT 1,3,CAST('1 Acacia Avenue' AS VARCHAR(50)) UNION ALL
SELECT 2,1,CAST('(01223) 654321' AS VARCHAR(50)) UNION ALL
SELECT 2,2,CAST('bill@example.com' AS VARCHAR(50)) 
)

/*The above Common Table Expressions are just for demo purposes and so you 
can see the assumptions. They will not work on SQL Server 2000. You just need 
the below.*/
SELECT P.UserName, 
       /*I've just used the Ids rather than bothering to join on ContactTypes*/
       MAX(CASE WHEN C.ContactTypeId = 1 then C.Value END) Tel,
       MAX(CASE WHEN C.ContactTypeId = 2 then C.Value END) Email,
       MAX(CASE WHEN C.ContactTypeId = 3 then C.Value END) PO
FROM Persons P
LEFT JOIN PersonContacts C ON C.PersonId = P.PersonId
GROUP BY P.PersonId,P.UserName

退货

UserName Tel                 Email               PO
-------- ------------------- ------------------- ------------------
Bob      (01223) 123456      bob@example.com     1 Acacia Avenue
Bill     (01223) 654321      bill@example.com    NULL
于 2011-04-24T17:43:52.483 回答
0

我想你想要这个：

SELECT p.username, email.value as email, tel.value as tel, po.value as po
FROM persons p
LEFT JOIN contacts as email ON contacts.person_id = person.id
LEFT JOIN contacts as tel ON contacts.person_id = person.id
LEFT JOIN contacts as po ON contacts.person_id = person.id
WHERE email.type = 'email'
AND tel.type = 'tel'
AND po.type = 'po'

所以你基本上加入了联系人表 3 次，因为联系人表包含 3 种不同形式的联系人。这是一种多态方法，它不能很好地映射到 SQL

此查询的结果应类似于：

username | email           | tel       | po
John     | john@john.com   | 012364342 | 1234AA
Sarah    | sarah@sarah.com | NULL      | NULL

我认为马丁的解决方案也可以，但我对 CASE-WHEN-THEN-END 不太满意

于 2011-04-24T17:57:48.380 回答
0

我们必须对您的架构进行猜测，因为您没有在问题的初始版本中向我们提供关键信息：

假定架构

  • 表：人员 - 用户名 (PK)，...
  • 表：联系人 - ContactType ('Tel', 'Email', 'PO'), ContactInfo, ContactID (PK), ...
  • 表：Junction - 用户名，ContactID - 组合上的 PK，每列上的 FK

可能的查询

SELECT P.UserName, T.Tel, E.Email, O.PO
  FROM Persons AS P
  LEFT JOIN (SELECT J.UserName, C.ContactInfo AS Tel
               FROM Contacts AS C
               JOIN Junction AS J ON C.ContactId = J.ContactID
              WHERE C.ContactType = 'Tel') AS T
       ON P.UserName = T.UserName
  LEFT JOIN (SELECT J.UserName, C.ContactInfo AS Email
               FROM Contacts AS C
               JOIN Junction AS J ON C.ContactId = J.ContactID
              WHERE C.ContactType = 'Email') AS E
       ON P.UserName = E.UserName
  LEFT JOIN (SELECT J.UserName, C.ContactInfo AS PO
               FROM Contacts AS C
               JOIN Junction AS J ON C.ContactId = J.ContactID
              WHERE C.ContactType = 'PO') AS O
       ON P.UserName = O.UserName

请注意，应该强制执行一些复杂的约束以使查询正常工作。第一个是给定的人有零个或一个电子邮件地址，零个或一个电话号码，以及零个或一个 PO（这是邮局地址吗？）。如果某人拥有多个这些条目中的任何一个，您根本不会告诉我们什么可能是合适的输出。并且约束执行起来很复杂，因为最简单的版本需要对用户名和联系人类型的组合进行唯一约束，但是这些列不会一起存储在任何单个表中。

于 2011-04-24T18:03:33.087 回答