MySQL Update – How to Remove from a Table Using Left Join and Alias

MySQLupdate

You can't specify target table 'cce_sa_fa' for update in FROM clause

This is the error that I received when tried to remove using the same table.

The following is the query that i have used to execute.

DELETE FROM `cce_sa_fa` WHERE id IN (SELECT cce_sa_fa.id FROM `cce_sa_fa` 
LEFT JOIN examinations ON examinations.id = cce_sa_fa.exam
WHERE `exam` IN (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,99,100,101,102,103,104,105,106,107,109,110,111,112,113,114,115,116,117,119,120,121,122,123,124,125,126,127,129,130,131,132,133,134,135,136,137,139,140,141,142,143,144,145,146,147,149,150,151,152,153,154,155,156,307,308,309) 
AND examinations.name != cce_sa_fa.name)

Best Answer

You can use JOIN in the FROM part instead of WHERE. This is the multi-table delete syntax, details in mysql docs: DELETESyntax.

Example:

DELETE fa.* 
FROM cce_sa_fa AS fa
  JOIN examinations AS ex 
    ON ex.id = fa.exam
WHERE fa.exam IN (1,2,...) 
  AND ex.name <> fa.name ;

Another way would be to convert the IN subquery to EXISTS:

DELETE 
FROM cce_sa_fa AS fa
WHERE EXISTS
      ( SELECT * 
        FROM examinations AS ex 
        WHERE ex.id = fa.exam
          AND ex.name <> fa.name 
      ) 
WHERE fa.exam IN (1,2,...) ;

Related Solutions

Mysql – Convert Oracle query to MySQL

Try using an UPDATE JOIN of the table against itself

UPDATE
    animal_table A
INNER JOIN
(
    SELECT
        category_id,summary_id,
        animal_nbr,animal_amount,'00' info3
    FROM animal_table
    WHERE animal_type = 'special'
) B USING (category_id,summary_id)
SET
    A.animal_info1 = B.animal_nbr,
    A.animal_info2 = B.animal_amount,
    A.animal_info3 = B.info3
WHERE
    A.animal_type = 'cats' AND
    A.category_id = 'foo';

Make sure that animal_table has a compound index on category_id and summary_id. If you do not have such an index, please run this:

ALTER TABLE animal_table ADD INDEX (category_id,summary_id);

UPDATE 2011-09-27 13:10 EDT

I just noticed that categrory_id 'foo' limits the dataset. Here is an updated refactoring of my answer ( I moved category_id = foo into the subquery )

UPDATE
    animal_table A
INNER JOIN
(
    SELECT
        category_id,summary_id,
        animal_nbr,animal_amount,'00' info3
    FROM animal_table
    WHERE animal_type = 'special'
    AND category_id = 'foo'
) B USING (category_id,summary_id)
SET
    A.animal_info1 = B.animal_nbr,
    A.animal_info2 = B.animal_amount,
    A.animal_info3 = B.info3
WHERE
    A.animal_type = 'cats';

I also recommend adding this additional index to accommodate the subquery

ALTER TABLE animal_table ADD INDEX (animal_type,category_id);

MySQL – Problem with Nested UPDATE Queries

Try

UPDATE Tab1 JOIN Tab2 ON Tab1.b = Tab2.b
SET Tab1.a = '3'
WHERE Tab1.c = '4'
;

Check the documentation for further information (look for 'multiple-table syntax'). An important point is:

If you use a multiple-table UPDATE statement involving InnoDB tables for which there are foreign key constraints, the MySQL optimizer might process tables in an order that differs from that of their parent/child relationship. In this case, the statement fails and rolls back. Instead, update a single table and rely on the ON UPDATE capabilities that InnoDB provides to cause the other tables to be modified accordingly. See Section 14.3.5.4, “FOREIGN KEY Constraints”.

You may check a similar example on SQLFiddle.

Best Answer

Related Solutions

Mysql – Convert Oracle query to MySQL

MySQL – Problem with Nested UPDATE Queries

Related Question