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

Alternatively,

select id from call
minus
select id from phone_number

Answer 2

There's several different ways of doing this, with varying efficiency, depending on how good your query optimiser is, and the relative size of your two tables:

This is the shortest statement, and may be quickest if your phone book is very short:

SELECT  *
FROM    Call
WHERE   phone_number NOT IN (SELECT phone_number FROM Phone_book)

alternatively (thanks to Alterlife)

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

or (thanks to WOPR)

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

(ignoring that, as others have said, it's normally best to select just the columns you want, not '*')

Answer 3

SELECT t1.ColumnID,
CASE 
    WHEN NOT EXISTS( SELECT t2.FieldText  
                     FROM Table t2 
                     WHERE t2.ColumnID = t1.ColumnID) 
    THEN t1.FieldText
    ELSE t2.FieldText
END FieldText       
FROM Table1 t1, Table2 t2

Answer 4

SELECT DISTINCT Call.id 
FROM Call 
LEFT OUTER JOIN Phone_book USING (id) 
WHERE Phone_book.id IS NULL

This will return the extra id-s that are missing in your Phone_book table.

Answer 5

I think

SELECT CALL.* FROM CALL LEFT JOIN Phone_book ON 
CALL.id = Phone_book.id WHERE Phone_book.name IS NULL

Answer 6

SELECT name, phone_number FROM Call a
WHERE a.phone_number NOT IN (SELECT b.phone_number FROM Phone_book b)