Question

我认为这应该有用，但正如你所看到的那样我得到了一个错误。这里的目标是通过使用两列定义重复项来删除重复项。第一个列表是所有dupes，第二个列表使用行ID来确保保留每个重复集中的一个。救命啊！

DELETE FROM tbl_events_temp WHERE tbl_events_temp.event_id IN (
    SELECT F.event_id
    FROM tbl_events_temp AS F
    WHERE EXISTS (
        SELECT airport_id, event_from, Count( event_id )
        FROM tbl_events_temp
        WHERE tbl_events_temp.airport_id = F.airport_id
        AND tbl_events_temp.event_from = F.event_from
        AND tbl_events_temp.airport_id != ''
        GROUP BY tbl_events_temp.airport_id, tbl_events_temp.event_from
        HAVING Count( tbl_events_temp.event_id ) >1
    )
)
AND tbl_events_temp.event_id NOT
IN (
    SELECT Min( event_id )
    FROM tbl_events_temp AS F
    WHERE EXISTS (
        SELECT airport_id, event_from, Count( event_id )
        FROM tbl_events_temp
        WHERE tbl_events_temp.airport_id = F.airport_id
        AND tbl_events_temp.event_from = F.event_from
        GROUP BY tbl_events_temp.airport_id, tbl_events_temp.event_from
        HAVING Count( tbl_events_temp.event_id ) >1
    )
    GROUP BY airport_id, event_from
)

错误：

MySQL said: Documentation
#1093 - You can't specify target table 'tbl_events_temp' for update in FROM clause

Answer 1

我认为你想要的是带有JOIN的DELETE，快速将它打包在一起，所以确保子查询正确识别要删除的记录：

DELETE tbl_events_temp
FROM tbl_events_temp
INNER JOIN (SELECT airport_id, event_from, Count(event_id),MIN(event_id)'event_id'
            FROM tbl_events_temp
            GROUP BY tbl_events_temp.airport_id, tbl_events_temp.event_from
            HAVING Count( tbl_events_temp.event_id ) >1
            )sub
ON tbl_events_temp.event_id = sub.event_id

使用以下代码删除重复项

1 个答案: