sql如何根据父集编号查询多集子集

这里用到了一个函数with

WITH CategoryInfo AS(
	SELECT StuId,StuName,StuParent FROM dbo.Class WHERE StuId = id
	UNION ALL
	SELECT a.StuId,a.StuName,a.StuParent FROM dbo.Class AS a,CategoryInfo AS b WHERE a.StuId = b.pid
	)
select * from CategoryInfo

这样就可以取到你想要的包括父集和子集了

你要是想根据查出来的内容做一些比如修改等操作可以这样写

declare @StuIds varchar(max);                         
WITH CategoryInfo AS(
	SELECT StuId,StuName,StuParent FROM dbo.Class WHERE StuId = id
	UNION ALL
	SELECT a.StuId,a.StuName,a.StuParent FROM dbo.Class AS a,CategoryInfo AS b WHERE a.StuId = b.pid
	)
select @StuIds=ISNULL(@StuIds+',','')+convert(varchar,StuId) from CategoryInfo
set @StuIds='UPDATE StuName from dbo.Class where StuId in('+@StuIds+')'
exec(@CompanyCodeIn)