SQL: Output all names which belong to a category where all the countries within it are the same

Question

I have the following table called Stores:

Name          |   Country   |   Category 
Pharmacy          Japan         Health
Green Vine        Italy         Dining         


        

Answer 1

You can use EXISTS :

SELECT t.*
FROM table t
WHERE EXISTS (SELECT 1 
              FROM table t1 
              WHERE t1.Country = t.Country AND 
                    t1.category = t.category AND
                    t1.Name <> t.Name
             );