Question

我需要从表中删除某些行。必须删除哪些行是我通过查询找到的。但是，it appears that you cannot do both operations (select and delete) in the same query：

目前，您无法从中删除表并从同一个表中选择在子查询中。

所以我不能这样做：

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

如何在纯MySQL中实现此记录清理？

服务器运行MySQL 5.1.39。

Answer 1

 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)

Answer 2

尝试使用连接

执行delete语句

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)

Answer 3

使用UPDATE标记要删除的行，然后DELETE实际删除它们。

UPDATE telefono SET marker_column='DELETE ME!!!!' WHERE telefono_id IN (...);
DELETE FROM telefono WHERE marker_column='DELETE ME!!!!';

选择和删除

3 个答案: