Determine if columns have duplicate values sql - sql-server

Question

I am trying to figure out a way to check if their is repeated values in rows that are shared.
Example:
HMOID Name Addon10 Addon15 Addon20
RFFF Blah img path1 img path2 img path1
For my example, I would like to check if any of the addons for RFFF have any repeated value. In my example above, 'RFFF' has two images that are the same in Addon10 and Addon20 (The images have a path. so currently, they look like
http://oc2-reatest.regalmed.local/ocupgrade52/images/NDL_SCAN_SR.PNG).
I would like to be able to do this for multiple rows. I thought the following would give me an idea how to begin:
select * from HlthPlan
Group By HMO1A, HMONM
Having COUNT(*) > 1
However, it throughs the following error:
Msg 8120, Level 16, State 1, Line 1
Column 'HlthPlan.HMOID' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.*
I am fairly new to SQL and any suggestions would be appreciated.

Answer 1

Don't include * for your select query. Only include the columns that you are using in GROUP BY
SELECT HMO1A, HMONM, COUNT(*) from HlthPlan
GROUP BY HMO1A, HMONM
HAVING COUNT(*) > 1;

Answer 2

With only three columns to check, assuming non-null values across a single row:
select * from HlthPlan
where Addon10 in (Addon15, Addon20) or Addon15 = Addon20
You can also use cross apply to pivot the values for grouping:
select HMOID, addon
from HlthPlan cross apply (
select addon
from (values (Addon01), (Addon02), (Addon03), ... (Addon20)) as pvt(addon)
) a
where addon is not null
group by HMOID, addon
having count(*) > 1;
http://rextester.com/QWIW87618
You'll get multiple rows for each HMOID where the are different groups of columns having the same value. By the way, reporting on the names of specific columns involved would add another degree of difficulty to the query.

Answer 3

One way you can check for this is using UNPIVOT to compare your results:
create table #hmo (hmoid varchar(6), name varchar(25), Addon10 varchar(25),
Addon15 varchar(25), addon20 varchar(25));
insert into #hmo
values ('RFFF', 'Blah','img path1', 'img path2', 'img path1');
select hmoid, name, addval, addcount = count(adds)
FROM #hmo
UNPIVOT
(
addval FOR adds IN
(addon10, addon15, addon20)
) as unpvt
group by hmoid, name, addval having count(*) > 1
Will give results:
hmoid name addval addcount
RFFF Blah img path1 2
This way you can check against every row in the table and will see any row that has any two or more columns with the same value.
This does have the potential to get tedious if you have a lot of columns; the easiest way to correct for that is to build your query dynamically using info from sys.tables and sys.columns.