SQL - find records from one table which don't exist in another

Question

I\'ve got the following two SQL tables (in MySQL):

Phone_book
+----+------+--------------+
| id | name | phone_number |
+----+------+--------------+
| 1  | J         


        

Answer 1

The code below would be a bit more efficient than the answers presented above when dealing with larger datasets.

SELECT * FROM Call WHERE 
NOT EXISTS (SELECT 'x' FROM Phone_book where 
Phone_book.phone_number = Call.phone_number)

Answer 2

SELECT Call.ID, Call.date, Call.phone_number 
FROM Call 
LEFT OUTER JOIN Phone_Book 
  ON (Call.phone_number=Phone_book.phone_number) 
  WHERE Phone_book.phone_number IS NULL

Should remove the subquery, allowing the query optimiser to work its magic.

Also, avoid "SELECT *" because it can break your code if someone alters the underlying tables or views (and it's inefficient).