SQL: How do you select only groups that do not contain a certain value?

Question

Say I have a table:

Restaurant locations: 

RESTAURANT_NO | RESTAURANT_LOCATION
-----------------------------------
1             |            City A
1               


        

Answer 1

SELECT DISTINCT
      Restaurant_no
FROM 
      TableX t
WHERE 
      NOT EXISTS
      ( SELECT *
        FROM TableX c
        WHERE c.Restaurant_no = t.Restaurant_no
          AND c.Restaurant_location = 'City C'
      )

Answer 2

One way:

SELECT RESTAURANT_NO FROM restaurant WHERE RESTAURANT_NO NOT IN
(SELECT RESTAURANT_NO FROM restaurant WHERE RESTAURANT_LOCATION = 'City C')

Answer 3

Use DISTINCT.

try this:

SELECT DISTINCT t.Restaurant_No
FROM Restaurant t
WHERE t.Restaurant_No NOT IN
       (SELECT s.Restaurant_No  
        FROM  Restaurant s
        WHERE s.RESTAURANT_LOCATION = 'City C')
ORDER BY t.Restaurant_No