Oracle sql Count distinct value over partition by?

Question

Sorry but I'm confused and can't get this to work.

I want to show the highest quantity of values that are the same value for each item,

What I mean is:- I have 70 pallets of an item, Item A Each pallet has a unique tag_id Each tag_id has a qty on it (qty_on_hand) Most of the time this qty_on_hand is the same for a lot of the pallets so for my 70 pallets I have 34 tags with a qty_on_hand of 60 6 tags with a qty_on_hand of 88 30 tags with a qty_on_hand of 80

I want to show the item number and the number highest number of tags, Above example would be Item A 34

But I need to do this for thousands of items in the warehouse. I can do a simple select i.qty_on_hand,count(qty_on_hand) from inventory i where i.zone_1 = 'BULKSTORE' and sku_id = '1961834100' group by qty_on_hand but it's for 1 item (sku_id) and then this still shows me that there are 3 different quantities_on_hand in the bulk store wereas I only want the highest for each sku.

I've looked at count distinct partition by etc, etc, but not been able to get it to work so any working examples would be great.

Hopefully I've not confused you too much. Thanks in advance Dean

Answer 1

Sample data, so we are talking about the same thing, would help.

Suppose "item" is identified by sku_id , and each pallet has a unique tag_id , it has a sku_id and a qty (quantity). And the table is called t .

Then something like

select sku_id, qty
from   ( 
         select   sku_id, qty,
                  dense_rank() over (partition by sku_id order by count(*) desc) as drk
         from     t
         group by sku_id, qty
       )
where  drk = 1
;

will give you what you need.