mysql – 使用GROUP BY删除重复项的查询

id_specific_price    id_product  
-------------------------------
            1                2  
            2                2  
            3                2  
            4                3  
            5                3  
            6                3  
            7                3

需要删除重复项,预期结果：

id_specific_price    id_product  
-------------------------------
            3                2  
            7                3

SELECT * 
  FROM ps_specific_price 
 WHERE id_specific_price NOT IN 
 (SELECT MAX(id_specific_price) 
    FROM ps_specific_price 
   GROUP BY id_product) 

工作,但

DELETE FROM ps_specific_price 
 WHERE id_specific_price NOT IN 
(SELECT MAX(id_specific_price) 
   FROM ps_specific_price 
  GROUP BY id_product)

才不是.有很多例子可以解决这个问题,但由于某种原因,我无法适应它.我相信它是GROUP BY.例如：

DELETE FROM ps_specific_price 
 WHERE id_specific_price NOT IN
 (SELECT MAX(p.id_specific_price) 
    FROM (SELECT * FROM ps_specific_price ) as p)
   GROUP BY id_product

我在哪里错了？ 最佳答案 如果您正在寻找MySQL的解决方案,那么您可以使用正确的multi table DELETE语法以及这样的JOIN

DELETE p
  FROM ps_specific_price p JOIN
(
  SELECT id_product,MAX(id_specific_price) id_specific_price
    FROM ps_specific_price
   GROUP BY id_product
) d 
   ON p.id_product = d.id_product
  AND p.id_specific_price <> d.id_specific_price;

结果：

| ID_SPECIFIC_PRICE | ID_PRODUCT |
|-------------------|------------|
|                 3 |          2 |
|                 7 |          3 |

这是SQLFiddle演示

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