MySQL 删除重复数据实例

SELECT order_id,product_id,COUNT(*) FROM product_comment GROUP BY order_id,product_id HAVING COUNT(*)>1;

CREATE TABLE bak_product_comment_18051801 LIKE product_comment;

INSERT INTO bak_product_comment_18051801 SELECT * FROM product_comment;

DELETE a
FROM product_comment a
JOIN(
    SELECT order_id,product_id,MIN(comment_id) AS comment_id
    FROM product_comment
    GROUP BY order_id,product_id
    HAVING COUNT(*)>=2
) b ON a.order_id=b.order_id AND a.product_id=b.product_id
AND a.comment_id>b.comment_id