SELECT and DELETE
I need to remove certain rows from a table. Which rows must be deleted is something I find out through a query. However, it appears that you cannot do both 开发者_JAVA技巧operations (select and delete) in the same query:
Currently, you cannot delete from a table and select from the same table in a subquery.
So I cannot do this:
DELETE
FROM telefono
WHERE telefono_id IN (
SELECT te.telefono_id
FROM telefono te
LEFT JOIN centro_telefono ce ON te.telefono_id=ce.telefono_id AND ce.telefono_id IS NOT NULL
LEFT JOIN contacto_telefono co ON te.telefono_id=co.telefono_id AND co.telefono_id IS NOT NULL
WHERE COALESCE(ce.telefono_id, co.telefono_id) IS NULL AND te.fecha_alta < DATE_SUB(NOW(), INTERVAL 1 DAY)
);
-- SQL Error (1093): You can't specify target table for update in FROM clause
How can I implement this record clean-up in pure MySQL?
The server runs MySQL 5.1.39.
Try doing the delete statement with the joins
DELETE te
FROM telefono as te
LEFT JOIN centro_telefono ce
ON te.telefono_id=ce.telefono_id AND ce.telefono_id IS NOT NULL
LEFT JOIN contacto_telefono co
ON te.telefono_id=co.telefono_id AND co.telefono_id IS NOT NULL
WHERE
COALESCE(ce.telefono_id, co.telefono_id) IS NULL
AND te.fecha_alta < DATE_SUB(NOW(), INTERVAL 1 DAY)
CREATE TEMPORARY TABLE tmptable
SELECT te.telefono_id
FROM telefono te
LEFT JOIN centro_telefono ce ON te.telefono_id=ce.telefono_id AND ce.telefono_id IS NOT NULL
LEFT JOIN contacto_telefono co ON te.telefono_id=co.telefono_id AND co.telefono_id IS NOT NULL
WHERE COALESCE(ce.telefono_id, co.telefono_id) IS NULL AND te.fecha_alta < DATE_SUB(NOW(), INTERVAL 1 DAY)
DELETE FROM telefono te
WHERE te.telefono_id IN (Select telefono_id from tmptable)
Use UPDATE
to mark rows for deletion, then DELETE
to actually delete them.
UPDATE telefono SET marker_column='DELETE ME!!!!' WHERE telefono_id IN (...);
DELETE FROM telefono WHERE marker_column='DELETE ME!!!!';
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