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MySQL: Select rows from one table that do not exist on another table

Posted on 2014-01-23
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1,010 Views
Last Modified: 2014-01-23
I want to select all rows from table2 where table2 has a value in "isbn" that does not exist on table1.

This does not return anything:
SELECT * FROM table2 JOIN table1 on table2.isbn = table1.isbn WHERE table2.isbn != table1.isbn

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Question by:hankknight
  • 2
3 Comments
 
LVL 4

Assisted Solution

by:ravikantninave
ravikantninave earned 400 total points
ID: 39804211
If the tables have compound primary keys, you'll have to use a "NOT EXISTS" clause

SELECT * 
  FROM TableA AS a 
 WHERE NOT EXISTS (
                   SELECT * 
                     FROM TableB b 
                    WHERE b.id1 = a.id1 
                          AND b.id2 = a.id2 
                          AND b.id3 = a.id3
                  );

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or
SELECT TableA.* FROM TableA LEFT JOIN TableB ON TableA.id = TableB.id WHERE TableB.id IS NULL

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Assisted Solution

by:Proud_Grandpa
Proud_Grandpa earned 100 total points
ID: 39804220
Would this work?

SELECT table2.* FROM table1, table2 WHERE table1.isbn NOT IN table2.isbn;
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LVL 4

Accepted Solution

by:
ravikantninave earned 400 total points
ID: 39804233
This works perfectly:

SELECT Table_2.* FROM Table_2 LEFT JOIN Table_1 ON Table_2.isbn = Table_1.isbn WHERE Table_1.isbn  IS NULL
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