[英]How to do a parent/child database 'roll-up'?
How do you properly go about rolling up and selecting all users for each parent company until there are no more parent companies? 您如何正确地汇总并选择每个母公司的所有用户,直到没有更多母公司?
I am using SQL Server 2008 R2 and I need to check if there is a @ParentID then select all the users for that company, if there is a @ParentID on that company do the same thing, ad infinity? 我正在使用SQL Server 2008 R2,我需要检查是否有@ParentID,然后选择该公司的所有用户,如果该公司上有@ParentID,则做同样的事情,广告无穷大?
Thanks. 谢谢。 I am completely new to Rollups but am just trying something like the below to get the basic query idea started.
我对汇总完全陌生,但只是尝试使用以下类似方法来开始基本的查询思路。
USE [DB]
DECLARE @UserName VARCHAR(250) = 'crusher@abc.com'
DECLARE @ParentID INT = -1
WHILE (@ParentID <> 0)
BEGIN
SELECT @ParentID = CASE
WHEN ParentCompanyID IS NULL
THEN 0
ELSE ParentCompanyID
END
FROM User2Company a
LEFT JOIN dbo.CompanyInfo b ON a.CompanyID = b.CompanyID
LEFT JOIN dbo.widgets ON a.companyid = widgets.companyid
WHERE a.UserName = @UserName
PRINT @ParentID
END
--SELECT * FROM CompanyInfo
--WHERE CompanyID = 100274
--SELECT *
--FROM CompanyInfo
--WHERE CompanyID = 100273
The commented code is just a hypothetical example of where the original query found a parent CompanyID of 100274... then THAT company found a parent CompanyID of 100273... until ultimately CompanyID 100273 had a ParentCompanyID of 0 in it's column. 注释的代码只是一个假设示例,该示例在原始查询中找到父公司ID为100274 ...然后该公司找到父公司ID为100273 ...直到最终公司ID 100273在其列中的父公司ID为0。
HOw is this typically done? 通常如何完成?
DESIRED Output from the first query might look like this: 第一个查询的期望输出可能如下所示:
100274
100273
0
At which point I would fetch all user's from those company id's. 此时,我将从这些公司ID中获取所有用户。
It's typically done with a recursive CTE: 通常通过递归CTE完成:
;WITH
tmp AS
(
SELECT CompanyID,
ParentCompanyID
FROM CompanyInfo
WHERE CompanyID = 100274
UNION ALL
SELECT com.CompanyID,
com.ParentCompanyID
FROM CompanyInfo com
INNER JOIN tmp tmp ON com.CompanyID = tmp.ParentCompanyID -- This is the recursive part
)
SELECT * FROM tmp
And as others have said, avoid using loops in SQL Server. 正如其他人所说,请避免在SQL Server中使用循环。 If you have to use loop, 99% of the time you are not using SQL Server properly.
如果必须使用循环,则有99%的时间没有正确使用SQL Server。
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