sql - 如何重用存储过程中的结果以提供给同一存储过程中的第二个选择

Question

我正在编写一个存储过程来获取整个屏幕的数据。我怎样才能重新使用一次选择的结果来输入第二次选择？这是出于性能原因

简化示例: 我有 4 张 table

1. 负责
2. Action(有 Responsible 的外键)
3. 组(有 Responsible 的外键)
4. 案例(有组的外键)

存储过程获取一个caseid来检索数据

首先select获取case、group及其相关responsible记录的详细信息:

select 
   Case.Date,
   Case.Name,
   Group.Name,
   Responsible.Name
   Responsible.ResponsibleID
from Case
inner join Group on Group.GroupID=Case.GroupID
inner join Responsible on Responsible.ResponsibleID=Group.ResponsibleID
where CaseID=@CaseID

第二个选择必须得到负责人被分配到的所有 Action 。我们只有 caseID，因此我们必须再次重建连接:

select Action.*  
from Case
inner join Group on Group.GroupID=Case.GroupID
inner join Responsible on Responsible.ResponsibleID=Group.ResponsibleID
inner join Action  on Action.ResponsibleID=Responsible.ResponsibleID
where CaseID=@CaseID

如果可以重用先前结果中的变量，则可以创建以下查询，这可能会提高性能:

Select * from Action where ResponsibleID={ResultSet1}.ResponsibleID

Answer 1

考虑将结果保存在表变量中。这将允许您对永久表中的结果集执行多个 SQL 操作。

DECLARE @Case TABLE
(
    [CaseDate] datetime,
    [CaseName]  varchar(100),
    [GroupName] varchar(100),
    [ResponsibleName] varchar(100),
    [ResponsibleID] int
)

--get all your case details
INSERT INTO @Case( [CaseDate],[CaseName],
                   [GroupName],[ResponsibleName],[ResponsibleID])
SELECT 
   Case.Date,
   Case.Name,
   Group.Name,
   Responsible.Name
   Responsible.ResponsibleID
FROM      Case
INNER JOIN Group ON Group.GroupID=Case.GroupID
INNER JOIN Responsible ON Responsible.ResponsibleID=Group.ResponsibleID
WHERE CaseID=@CaseID


--now get the Action details for the previous case; 
--are we absolutely sure there is only one row? then an INNER JOIN 
SELECT A.*  
FROM   Action  AS [A] 
INNER JOIN @Case AS C ON A.ResponsibleID=C.ResponsibleID

-- or guard against multiple results in @Case
SELECT A.* FROM Action AS [A] 
WHERE A.ResponsibleID = (SELECT TOP 1 ResponsibleID FROM @Case)