Find only common column items in a table WITHIN the same group - sql

Question

I have a table that has 3 columns
Plate_Id, Prod_id and Location
You can say that the plate_id is the "header" column.
The prod_id groups the 'locations' together for a particular 'plate_id'
Given a particular set of values, I only want to pick locations that are 'COMMON' amongst prod_ids for a particular plate_id.
NOTE: My table can have multiple plate_ids
I am close, but its not perfect.
I tried to isolate the smallest group for a given plate_id and then tried to inner join it with the original list, but it fails for the scenario where I have 3 prod_ids and a location is common for even one group(i need only locations that are strictly in every prod_id)
Following is the result I desire, based on the how far I have gotten so far,
-- DESIRED RESULT:
-- plate_id location
-- 100 1
-- 100 2
-- 200 3
-- 200 4
-- 300 1
-- 300 2
-- 300 5
create table #AllTab
(
plate_id int,
prod_id int,
location int
)
insert into #AllTab
values
(100,10, 1),
(100,10, 2),
(100,10, 3),
(100,10, 4),
(100,20, 1),
(100,20, 2),
(100,20, 3),
(100,20, 4),
(100,20, 5),
(100,20, 6),
(100,20, 9),
(100,30, 1),
(100,30, 2),
(100,30, 9),
(100,40, 1),
(100,40, 2),
(100,40, 12),
(100,40, 14),
(100,40, 1),
(100,40, 2),
(100,40, 25),
(100,40, 30),
-----------------
(200,10, 1),
(200,10, 2),
(200,10, 3),
(200,10, 4),
(200,20, 1),
(200,20, 2),
(200,20, 3),
(200,20, 4),
(200,20, 5),
(200,20, 6),
(200,20, 7),
(200,30, 3),
(200,30, 4),
(200,30, 9),
-----------------
(300,10, 1),
(300,10, 2),
(300,10, 3),
(300,10, 5),
(300,20, 1),
(300,20, 2),
(300,20, 3),
(300,20, 4),
(300,20, 5),
(300,20, 6),
(300,20, 7),
(300,20, 9),
(300,30, 1),
(300,30, 2),
(300,30, 5)
-- The #SubTab table isolates the smallest group from the above table
-- for a particular plate_id
create table #SubTab
(
plate_id int,
prod_id int,
location int
)
insert into #SubTab
values
(100,30, 1),
(100,30, 2),
(100,30, 9),
------------
(200,30, 3),
(200,30, 4),
(200,30, 9),
------------
(300,30, 1),
(300,30, 2),
(300,30, 5)
select distinct pr.plate_id, pr.prod_id, pr.location from #SubTab pr
inner join #AllTab pl on pr.plate_id = pl.plate_id
and pr.location = pl.location
where pr.Prod_Id <> pl.prod_id
group by pr.plate_id, pr.prod_id, pr.location

Answer 1

This query returns the locations that are in all the products for a given plate:
select plate_id, location
from #alltab a
group by plate_id, location
having count(distinct prod_id) = (select count(distinct prod_id) from #alltab a2 where a2.plate_id = a.plate_id);
This assumes no duplicates in the table -- a reasonable assumption given your data.
Here is a rextester.

Answer 2

try this:
;with cte1
AS
(
Select Plate_Id,Count(DISTINCT prod_id) as ProdCount
From #AllTab
Group by Plate_Id
)
,cte2
AS
(
Select Plate_Id,Location,Count(Location) As LocCount
from #AllTab
Group by Plate_Id,Location
)
SELECT t1.plate_id ,t2.location
FROM cte1 t1 JOIN cte2 t2
ON t1.Plate_Id =t2.Plate_Id
Where LocCount>=ProdCount

Answer 3

I have a solution, it might be a tad lengthy, but works,
SELECT
SubGroupCounts.plate_id,
LocationSubGroupCounts.location
FROM
(-- Number of sub-grouping relative to main grouping
SELECT
plate_id,
count(distinct prod_id) as num
FROM
AllTab
GROUP BY
plate_id) SubGroupCounts
INNER JOIN
(-- Count the number of sub-groups each location appears in
SELECT
plate_id,
Location,
COUNT(distinct prod_id) AS num
FROM
AllTab
GROUP BY
Location, plate_id) LocationSubGroupCounts ON LocationSubGroupCounts.plate_id = SubGroupCounts.plate_id
AND LocationSubGroupCounts.num = SubGroupCounts.num