Question

I have this query that should:

create a listing that identifies different items in the inventory
table on the number of colors available for each option

But I’m getting an error saying:

Error at Command Line:167 Column:66 Error report: SQL Error:
ORA-00904: “INV”.”ITEM_ID”: invalid identifier
00904. 00000 – “%s: invalid identifier”

SELECT inv.inv_id, 
item1.item_id, 
(SELECT COUNT(*) 
FROM (SELECT DISTINCT i.color FROM inventory i WHERE i.item_id = inv.item_id))
FROM inventory inv 
INNER JOIN item item1 
ON item1.item_id = inv.item_id
GROUP BY inv.inv_id, item1.item_id;

Answer 1

It sounds like you just want

SELECT inv.inv_id,
       item1.item_id,
       COUNT( distinct inv.color )
  FROM inventory inv
       JOIN item item1 ON (item1.item_id = inv.item_id)
 GROUP BY inv.inv_id, item1.item_id

There doesn’t seem to be any reason to hit the inventory table again in a subquery.