查询、子查询并用作子查询中的变量答案

【问题标题】：Query, subquery and using as variables from subquery查询、子查询并用作子查询中的变量
【发布时间】：2013-04-02 20:19:10
【问题描述】：

是不是可以使用"as [item] 然后在查询中使用item变量。

例如：

select c.category as [category],c.orderby as [CatOrder], m.masterno, m.master
,-- select OUT (select count(*) from    rentalitem       ri  with (nolock), 
            rentalitemstatus ris with (nolock), 
            rentalstatus     rs  with (nolock)
    where   ri.rentalitemid    = ris.rentalitemid
            and   ris.rentalstatusid = rs.rentalstatusid
            and   ri.masterid        = m.masterid
            and   rs.statustype     in ('OUT', 'INTRANSIT', 'ONTRUCK'))  as [qtyout] 
,-- select OWNED owned=
(select top 1 mwq.qty                                           
    from    masterwhqty mwq                                              
    where   mwq.masterid    = m.masterid) 

, -([owned]-[qtyout]) as [Variance]

from master m 
    inner join category c on c.categoryid=m.categoryid and c.categoryid=@category
    inner join inventorydepartment d on c.inventorydepartment=@department

在计算方差时，我似乎无法使用 qtyout 或 own。我该怎么做？

【问题讨论】：

标签： sql sql-server sql-server-2008 reporting-services

【解决方案1】：

您也可以使用表变量，然后像上面尝试的那样引用该表变量....这是来自MSDN 的示例

USE AdventureWorks2012;
GO
DECLARE @MyTableVar table(
    EmpID int NOT NULL,
    OldVacationHours int,
    NewVacationHours int,
    ModifiedDate datetime);
UPDATE TOP (10) HumanResources.Employee
SET VacationHours = VacationHours * 1.25,
    ModifiedDate = GETDATE() 
OUTPUT inserted.BusinessEntityID,
       deleted.VacationHours,
       inserted.VacationHours,
       inserted.ModifiedDate
INTO @MyTableVar;
--Display the result set of the table variable.
SELECT EmpID, OldVacationHours, NewVacationHours, ModifiedDate
FROM @MyTableVar;
GO
--Display the result set of the table.
SELECT TOP (10) BusinessEntityID, VacationHours, ModifiedDate
FROM HumanResources.Employee;
GO

【讨论】：

【解决方案2】：

需要将您的计算字段移动到子查询中，然后在外部查询中通过它们的别名使用它们。

select subquery.*, -([owned]-[qtyout]) as [Variance]
from
(
    select c.category as [category],c.orderby as [CatOrder], m.masterno, m.master
    ,-- select OUT (select count(*) from    rentalitem       ri  with (nolock), 
                rentalitemstatus ris with (nolock), 
                rentalstatus     rs  with (nolock)
        where   ri.rentalitemid    = ris.rentalitemid
                and   ris.rentalstatusid = rs.rentalstatusid
                and   ri.masterid        = m.masterid
                and   rs.statustype     in ('OUT', 'INTRANSIT', 'ONTRUCK'))  as [qtyout] 
    ,-- select OWNED owned=
    (select top 1 mwq.qty                                           
        from    masterwhqty mwq                                              
        where   mwq.masterid    = m.masterid) as [owned]

    from master m 
        inner join category c on c.categoryid=m.categoryid and c.categoryid=@category
        inner join inventorydepartment d on c.inventorydepartment=@department
) as subquery

【讨论】：

【解决方案3】：

你需要使用子查询：

select t.*,
       ([owned]-[qtyout]) as [Variance]
from (<something like your query here
     ) t

您的查询，即使没有 cmets，也不太有意义（select OUT (select . . . 代表）。但是，您的问题的答案是在子查询或 CTE 中定义基本变量，然后随后使用它们。

而且，您将差异称为“差异”。如您所知，您正在重新定义术语 (http://en.wikipedia.org/wiki/Variance) 的统计含义，它基于差异的平方。

【讨论】：