范围派生表的

Question

我有一个相当复杂的SQL查询，在这里我们需要返回的列数，并且每一个代表从表中不同的行。所有派生表都需要通过值进行过滤，以便仅为该帐户恢复一个表。下面的工程伟大：

SELECT CurrentBalance.Value, 
     CurrentBalance.Customer, 
     Debt30Balance.Value AS Expr1, 
     Debt30Balance.Customer AS Expr2, 
     Debt60Balance.Value AS Expr3, 
     Debt60Balance.Customer AS Expr4, 
     Debt90Balance.Value AS Expr5, 
     Debt90Balance.Customer AS Expr6, 
     WIPCurrent.Value  AS Expr7, 
     WIPCurrent.Customer AS Expr8, 
     WIP30Days.Value  AS Expr9, 
     WIP30Days.Customer  AS Expr10, 
     WIP60Days.Value  AS Expr11, 
     WIP60Days.Customer  AS Expr12, 
     WIP90Days.Value  AS Expr13, 
     WIP90Days.Customer  AS Expr14 
FROM (SELECT TOP (1) Value, 
         Customer 
     FROM DebtBreakdown 
     WHERE (Customer = @CustomerID) 
       AND (Type = 0) 
     ORDER BY Timestamp DESC) AS CurrentBalance 
     INNER JOIN (SELECT TOP (1) Value, 
            Customer 
        FROM DebtBreakdown AS DebtBreakdown_7 
        WHERE (Customer = @CustomerID) 
          AND (Type = 1) 
        ORDER BY Timestamp DESC) AS Debt30Balance 
     ON CurrentBalance.Customer = Debt30Balance.Customer 
     INNER JOIN (SELECT TOP (1) Value, 
            Customer 
        FROM DebtBreakdown AS DebtBreakdown_6 
        WHERE (Customer = @CustomerID) 
          AND (Type = 2) 
        ORDER BY Timestamp DESC) AS Debt60Balance 
     ON Debt30Balance.Customer = Debt60Balance.Customer 
     INNER JOIN (SELECT TOP (1) Value, 
            Customer 
        FROM DebtBreakdown AS DebtBreakdown_5 
        WHERE (Customer = @CustomerID) 
          AND (Type = 3) 
        ORDER BY Timestamp DESC) AS Debt90Balance 
     ON Debt60Balance.Customer = Debt90Balance.Customer 
     INNER JOIN (SELECT TOP (1) Value, 
            Customer 
        FROM DebtBreakdown AS DebtBreakdown_4 
        WHERE (Customer = @CustomerID) 
          AND (Type = 4) 
        ORDER BY Timestamp DESC) AS WIPCurrent 
     ON Debt90Balance.Customer = WIPCurrent.Customer 
     INNER JOIN (SELECT TOP (1) Value, 
            Customer 
        FROM DebtBreakdown AS DebtBreakdown_3 
        WHERE (Customer = @CustomerID) 
          AND (Type = 5) 
        ORDER BY Timestamp DESC) AS WIP30Days 
     ON WIPCurrent.Customer = WIP30Days.Customer 
     INNER JOIN (SELECT TOP (1) Value, 
            Customer 
        FROM DebtBreakdown AS DebtBreakdown_2 
        WHERE (Customer = @CustomerID) 
          AND (Type = 6) 
        ORDER BY Timestamp DESC) AS WIP60Days 
     ON WIP30Days.Customer = WIP60Days.Customer 
     INNER JOIN (SELECT TOP (1) Value, 
            Customer 
        FROM DebtBreakdown AS DebtBreakdown_1 
        WHERE (Customer = @CustomerID) 
          AND (Type = 7) 
        ORDER BY Timestamp DESC) AS WIP90Days 
     ON WIP60Days.Customer = WIP90Days.Customer 

但是，我需要能够过滤除给定的参数以外的东西。基本上，我想要做的是选择客户记录，给定一个参数，如客户名称，选择ID，然后将其用于派生表。我已经尝试过Join，但派生表不在任何连接的范围内。

任何想法？

Answer 1

如果你是至少在SQL Server 2005（似乎从括号TOP表达有可能的），你可以使用公用表表达式，而不是派生表的。

/*Any previous statement must be terminated with a semi colon*/ 
WITH CurrentBalance 
    AS (SELECT TOP (1) Value, 
         Customer 
     FROM DebtBreakdown 
     WHERE (Customer = @CustomerID) 
       AND (Type = 0) 
     ORDER BY Timestamp DESC), /*Comma delimit CTE definitions*/ 
    Debt30Balance 
    AS (SELECT TOP (1) Value, 
         Customer 
     FROM DebtBreakdown AS DebtBreakdown_7 
     WHERE (Customer = @CustomerID) 
       AND (Type = 1) 
     ORDER BY Timestamp DESC) 
     /* ETC ETC */ 

您可以在同一查询中多次引用CTE。