Question

I have two columns in my Items table ‘Category’, ‘Category2’, the two columns contain, essentially the same information. If I had designed the database I would have created a separate table for categories and added items to categories based based off of that table, unfortunately I didn’t create the database and I can’t change it now but I think there is still a way to do what I want to do.

An example of the table is shown below

Category             Category2
------------------   -----------------
truck                full size - pickup
full size - pickup   truck
Sedan                Import - Sedan
Convertible          Domestic - Coupe

I want to run a query to count the total number of trucks, sedans, full size – pickup, etc. I tried the below query but it grouped the two columns separately

SELECT Category, Count(*) as Count
FROM Items
GROUP BY Category, Category2

Answer 1

Just dump both categories into a single column before grouping.

SELECT Category, Count(*) as TheCount
FROM
(
  SELECT Category1 as Category
  FROM Items
  UNION ALL
  SELECT Category2
  FROM Items
) sub
GROUP BY Category