insert into select from inner join where not exists - sql

Question

I have this SQL Server code. Everything works except it duplicates rows with same RightsId and UserId. The where not exists clause is not working.
Any help is appreciated.
INSERT INTO dbo.UserAccessRights (Id, UserId, RightType, RightsId, CreatedOn, CreatedBy)
SELECT DISTINCT
NEWID(),
#changedUserId,
N'Process ' + #rightsTypeSuffix,
ptm.ProcessInstance_id,
getdate(),
#loggedInUserId
FROM
dbo.ProcessTeamMembers ptm WITH (NOLOCK)
INNER JOIN
dbo.Users u WITH (NOLOCK) ON ptm.TeamMemberProfile_id = u.ProfileID
AND u.Id = #changedUserId
AND ptm.TenantId = #tenantId
INNER JOIN
dbo.ProcessInstances p_i WITH (NOLOCK) ON p_i.Id = ptm.ProcessInstance_id
AND p_i.DeletedOn IS NULL
WHERE
NOT EXISTS (SELECT *
FROM UserAccessRights uar WITH (NOLOCK)
WHERE uar.UserId = #changedUserId
AND uar.RightsId = ptm.ProcessInstance_id)

Answer 1

Your duplicates are probably coming from within the query, rather than from existing rows in the table. Possibly, the problem is that the select distinct isn't doing anything -- because newid() is always unique.
My recommendation is to change the id column to have a default value of newid(). Then you don't need to insert it and the select distinct will work. Absent that, you can fix the query:
INSERT INTO dbo.UserAccessRights (Id, UserId, RightType, RightsId, CreatedOn, CreatedBy)
SELECT DISTINCT NEWID(), #changedUserId, N'Process ' + #rightsTypeSuffix,
ProcessInstance_id, getdate(), #loggedInUserId
FROM (SELECT DISTINCT ptm.ProcessInstance_id
FROM dbo.ProcessTeamMembers ptm WITH (NOLOCK) INNER JOIN
dbo.Users u WITH (NOLOCK)
ON ptm.TeamMemberProfile_id = u.ProfileID AND
u.Id = #changedUserId AND
ptm.TenantId = #tenantId INNER JOIN
dbo.ProcessInstances p_i WITH (NOLOCK)
ON p_i.Id = ptm.ProcessInstance_id AND
p_i.DeletedOn IS NULL
WHERE NOT EXISTS (SELECT 1
FROM UserAccessRights uar WITH (NOLOCK)
WHERE uar.UserId = #changedUserId AND
uar.RightsId = ptm.ProcessInstance_id
)
) t;
Hmmm, as I think about this, perhaps you should be using TOP 1 rather than SELECT DISTINCT. I'm not sure which columns cause the problem on the distinct, but you are inserting the same value in many columns, so more than one row might cause an issue.

Answer 2

Try the "Left Excluding Join" (See Visual Representation of SQL Joins) instead of the WHERE NOT EXISTS clause.
INSERT INTO dbo.UserAccessRights (Id, UserId, RightType, RightsId, CreatedOn, CreatedBy)
SELECT DISTINCT
NEWID(),
#changedUserId,
N'Process ' + #rightsTypeSuffix,
ptm.ProcessInstance_id,
getdate(),
#loggedInUserId
FROM
dbo.ProcessTeamMembers ptm
INNER JOIN
dbo.Users u ON ptm.TeamMemberProfile_id = u.ProfileID
AND u.Id = #changedUserId
AND ptm.TenantId = #tenantId
INNER JOIN
dbo.ProcessInstances p_i ON p_i.Id = ptm.ProcessInstance_id
AND p_i.DeletedOn IS NULL
LEFT JOIN UserAccessRights uar
ON uar.UserId = u.Id
AND uar.RightsId = ptm.ProcessInstance_id
WHERE
uar.Id IS NULL -- Replace with the actual pkey on UserAccessRights if not Id