Select all users from subgroups in T-SQL query [duplicate] - sql-server

Question

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SQL Server recursive self join
(1 answer)
Closed 3 years ago.
I have a SQL Server table that holds groups and subgroups that I am using to define user permissions in application. What I am trying to accomplish is to select all users ids from all subgroups based on used id assigned to group.
I have tried with this query but it only shows one level of subgroup users.
SET #UserIds =
ISNULL(
STUFF((SELECT ',' + CAST(tbl.UserID AS VARCHAR(MAX))
FROM
(SELECT grpUser.UserId AS UserID
FROM dbo.GroupUser grpUser
INNER JOIN (SELECT subGrp.Id, subGrp.GroupName
FROM dbo.Groups grp
INNER JOIN dbo.GroupUser guser ON grp.Id = guser.GroupId
AND guser.UserId = #UserId
INNER JOIN dbo.Groups subGrp ON grp.Id = subGrp.ParentGroupId) tbl ON grpUser.GroupId = tbl.Id) AS tbl
FOR XML PATH('')), 1, 1, ''), '')
I am struggling to get users ids in all subgroups. Number of subgroups is not defined. Is there a way to do in sql or should I shift this part to application side? Thank you for any advice.

Answer 1

Finally I came up with this code. Thank you for hint.
declare #UserGroupId int;
Set #UserGroupId = (Select GroupId from GroupUser gu
left join dbo.Groups gr on gu.GroupId = gr.id
where UserId = #UserId and gr.IsDeleted = 0)
declare #UsersGroups Table (
Id int not null,
GroupName nvarchar(50) not null
)
;WITH grp AS
(
SELECT Id, GroupName
FROM Groups
WHERE ParentGroupId = 1
UNION ALL
SELECT g.Id, g.GroupName
FROM Groups g
INNER JOIN dbo.GroupUser guser ON g.Id = guser.GroupId
INNER JOIN grp ON g.ParentGroupId = grp.Id
)
Insert into #UsersGroups
SELECT Id, GroupName
FROM grp
SET #UserIds = ISNULL(STUFF(( SELECT ',' + CAST(tbl.UserID AS VARCHAR(max)) FROM (
SELECT grpUser.UserId AS UserID FROM dbo.GroupUser grpUser
INNER JOIN ( SELECT * FROM #UsersGroups
) tbl ON grpUser.GroupId = tbl.Id
) AS tbl FOR XML PATH('') ), 1, 1, ''), '')