Question

我有一个带有重复的products_model字段的表（产品）。我需要将它们改为一些新的价值。我可以选择它们：SELECT * FROM products GROUP BY products_model HAVING count(*) >=2

我需要更改products_model = products_model + RANDOM NUMBER

谢谢

Answer 1

鉴于两个字段都是VARCHARS，这可以完成工作，将products_model和products_id连接到下划线

update products p1,
    products p2 
set 
    p1.products_model = concat(p1.products_model, '_', p1.products_id),
    p2.products_model = concat(p2.products_model, '_', p2.products_id)
where
    p1.products_model = p2.products_model
        and p1.products_id > p2.products_id

在：

id products_model products_id
1   A   a
2   A   b
3   B   a
4   C   a
5   C   b

后：

id products_model products_id
1   A_a a
2   A_b b
3   B   a
4   C_a a
5   C_b b

Answer 2

这使用变量为具有相同模型的产品分配序号。然后它会更新除第一个之外的所有内容，以便在型号名称后面显示序号：

update products p join
       (select p.*,
               (@rn := if(@pm = products_model, @rn + 1,
                          if(@pm := products_model, 1, 1)
                         )
               ) as seqnum
        from products p
        order by products_model
       ) pp
       on p.id = pp.id cross join
       (select @pm := '', @rn := 0) vars
    set products_model = concat_ws('_', products_model, seqnum)
    where seqnum > 1;

mysql修改重复的字段

2 个答案: