能否在SQL查询中使用相同的列两次使用不同的过滤器？

Question

我正在为客户创建报告。 在其中，我需要合并来自4个表的信息。 直到最后一张表（我只使用一列），一切都很好。 此列包含电话和电子邮件（全部合而为一）。 我需要在单独的列中显示电子邮件地址和电话号码，但它们来自同一列。

我可以同时显示它们，但是它们显示在单独的行中。 我也可以复制该列，然后在excel中对其进行排序，但是客户需要能够自己完成此操作，而无需在以后进行编辑。

    SELECT CustomerProcessO.GID,
           CustomerProcessO.FOIF,
           Customers.FirstName,
           Customers.LastName,
           SalesPersons.FirstName,
           SalesPersons.LastName,
           DynamicListData.DataContent AS Email,
           DynamicListData.DataContent AS Phone
      FROM CustomerProcessO
LEFT OUTER JOIN Customers ON CustomerProcessO.id = Customers.id
LEFT OUTER JOIN SalesPersons ON CustomerProcessO.GIDSalesPerson = SalesPersons.GID
LEFT OUTER JOIN DynamicListData ON ParentId = Customers.id
     WHERE DynamicListData.KeyField = 'EMAILS'
        OR DynamicListData.KeyField = 'PHONES'

我得到的结果是正确的，但我在两行中分别得到了电话号码和电子邮件。 我需要一栏包含电子邮件，一栏包含电话号码

Answer 1

您可以两次连接同一张表：

SELECT dld1.DataContent AS Email, dld2.DataContent AS Phone
...
LEFT JOIN DynamicListData dld1 ON dld1.ParentId = Customers.id AND dld1.KeyField = 'EMAILS'
LEFT JOIN DynamicListData dld2 ON dld2.ParentId = Customers.id AND dld2.KeyField = 'PHONES'

Answer 2

SELECT        CustomerProcessO.GID, CustomerProcessO.FOIF, Customers.FirstName, Customers.LastName, SalesPersons.FirstName, SalesPersons.LastName, 
DLD1.Phone, DLD2.Email
FROM            CustomerProcessO 
LEFT OUTER JOIN Customers ON CustomerProcessO.id = Customers.id 
LEFT OUTER JOIN SalesPersons ON CustomerProcessO.GIDSalesPerson = SalesPersons.GID 
LEFT OUTER JOIN (SELECT ParentId, KeyField, DataContent AS [Phone] FROM DynamicListDate) DLD1 ON DLD1.ParentId = Customers.id AND DLD1.KeyField = 'PHONES'
LEFT OUTER JOIN (SELECT ParentId, KeyField, DataContent AS [Email] FROM DynamicListDate) DLD2 ON DLD2.ParentId = Customers.id AND DLD2.KeyField = 'EMAILS'