MySQL中删除重复数据只保留一条

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本文介绍如何使用SQL查询和删除数据库表中的重复记录，并提供了一种避免异常的方法，即通过创建中间表来解决删除过程中出现的问题。

使用SQL删除表中重复数据（单字段）：
1.查询重复数据：

SELECT
    *
FROM
    info_1688
WHERE
    storeURL IN (
        SELECT
            storeURL
        FROM
            info_1688
        GROUP BY
            storeURL
        HAVING
            COUNT(storeURL) > 1
    )

2.删除重复数据：

DELETE
FROM
    info_1688
WHERE
    storeURL IN (

        SELECT
            storeURL
        FROM
            info_1688
        GROUP BY
            storeURL
        HAVING
            COUNT(id) > 1

    )
AND id NOT IN (

    SELECT
        MIN(id) AS id 
    FROM
        info_1688
    GROUP BY
        storeURL
    HAVING
        COUNT(id) > 1

)

Mysql异常：you can’t specify target table ‘info_1688’ for update in FROM clause
解决方法：select的结果再通过一个中间表select，可以避免此错误

DELETE
FROM
    info_1688
WHERE
    storeURL IN (
    SELECT storeURL FROM (
        SELECT
            storeURL
        FROM
            info_1688
        GROUP BY
            storeURL
        HAVING
            COUNT(id) > 1
    ) AS tab1
    )
AND id NOT IN (
    SELECT id FROM (
        SELECT
        MIN(id) AS id 
        FROM
        info_1688
        GROUP BY
        storeURL
        HAVING
        COUNT(id) > 1
    ) AS tab2
)