Can anyone help me with a GROUP BY issue? - sql

Question

I have this query:
SELECT
tc.dv_task,
tc.dv_ci_item,
STUFF((
SELECT ',' + lob.name
FROM u_cmdb_ci_line_of_business lob
where lob.sys_id = tc.ci_item
GROUP BY tc.dv_task
FOR XML PATH('') ), 1, 1, '') AS LOBs
FROM task_ci tc
INNER JOIN u_cmdb_ci_line_of_business lob on tc.ci_item = lob.sys_id
It returns the following error: Msg 164, Level 15, State 1, Line 8
Each GROUP BY expression must contain at least one column that is not an outer reference.
I'm using Microsoft SQL Server 2016 (SP2-GDR) (KB4505220) - 13.0.5101.9 (X64)
Here's what I'm trying to accomplish: I have two tables task_ci (tc) and u_cmdb_line_of_business (lob). The tables join by tc.ci_item = lob.sys_id. For each dv_task on the tc table, I want one line that lists, in a comma-separated field, the related ci_items from the lob table. That's why I'm trying to group by dv_task.
If I take out the group by, I get this:
tc.dv_task LOBs (Stuff field)
123456 lob.ci_item 1
123456 lob.ci_item 2
I want this:
dv_task LOBs (Stuff field)
123456 lob. ci_item 1, lob.ci_item 2
But when I add that group by, as an attempt to get things in one row, I get that error. Hope that makes sense.
Can anyone tell me what I'm doing wrong?
EDIT: 03/23
Okay, I got it, I just changed it up to substring like this
select
inc.number,
substring((select ', ' + lob.name from task_ci tc
join u_cmdb_ci_line_of_business lob on lob.sys_id = tc.ci_item
where inc.sys_id = tc.task
for XML PATH('')),2,1000) as lob_sysid
from incident inc
where inc.number = 'INC1157655'
I'm still not sure what I was doing wrong with the STUFF but I'll try it with the different table to see how it works.
Thanks for the help.

Answer 1

I don't think you need the JOIN in the outer query:
SELECT tc.dv_task, tc.dv_ci_item,
STUFF((SELECT ',' + lob.name
FROM u_cmdb_ci_line_of_business lob
WHERE lob.sys_id = tc.ci_item
FOR XML PATH('')
), 1, 1, '') AS LOBs
FROM task_ci tc;

Answer 2

Okay, I got it, I just changed it up to substring like this
select
inc.number,
substring((select ', ' + lob.name from task_ci tc
join u_cmdb_ci_line_of_business lob on lob.sys_id = tc.ci_item
where inc.sys_id = tc.task
for XML PATH('')),2,1000) as lob_sysid
from incident inc
where inc.number = 'INC1157655'
I'm still not sure what I was doing wrong with the STUFF but I'll try it with the different table to see how it works.
Thanks for the help.