Question

我的查询完美无缺：

SELECT *
FROM Customer
WHERE SacCode IN
(
    SELECT SacCode
    FROM SacCode
    WHERE ResellerCorporateID = 392
    ORDER BY SacCode
)
AND CustomerID IN
(
    SELECT CxID
    FROM CustAppointments
    WHERE AppRoomID IN
    (
        SELECT AppRoomID
        FROM ClinicRooms
        WHERE ClinID IN
        (
            SELECT ClinID
            FROM AppClinics
            WHERE ClinDate >='20090101'
            AND ClinDate <='20091119'
        )
    )
)

但是，我需要查看ClinDate的值（在最后一个嵌套查询中）...

我该怎么做？

感谢。

Answer 1

我使用连接重写查询。然后，您可以访问任何已连接表中的任何数据。

例如，您可以像这样重写您的查询：

SELECT c.*, ac.ClinDate
FROM Customer c
  JOIN SacCode sc ON sc.SacCode = c.SacCode
  JOIN CustAppointments ca ON ca.CustomerID = c.CustomerID
  JOIN ClinicRooms cr ON cr.AppRoomID = ca.AppRoomID
  JOIN AppClinic ac ON ac.ClinID = cr.ClinID
WHERE ac.ClinDate >='20090101'
  AND ac.ClinDate <='20091119'
  AND sc.ResellerCorporateID = 392

Answer 2

认为我在FROM语句中使用派生表而不是3个深层嵌套查询，将允许您访问值并且看起来会更好。

Answer 3

您需要将子选项复制到FROM子句或使用JOIN重写查询。

Answer 4

看起来应该是这样的：

SELECT c.*, a.ClinDate

FROM Customer c

inner join CustAppointments ca
inner join ClinicRooms cr
inner join AppClinics a

where c.SacCode IN
(
    SELECT SacCode
    FROM SacCode
    WHERE ResellerCorporateID = 392
    ORDER BY SacCode
)

and c.CustomerID = ca.CxID
and ca.AppRoomID = cr.AppRoomID
and cr.ClinID = a.ClinID

and a.ClinDate >='20090101' 
and a.ClinDate <='20091119'

嵌套查询的麻烦

4 个答案: