mysql修改重复字段

Question

我有一个表（产品）有重复的products_model字段。 我需要将它们更改为一些新的值。 我可以选择他们：SELECT * FROM products GROUP BY products_model HAVING count(*) >=2

我需要改变products_model = products_model + RANDOM NUMBER

谢谢

Answer 1

鉴于这两个领域是VARCHAR处理这样做的工作，串联products_model并用下划线

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 

products_id

之前：

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

这将使用变量分配一个序列号，产品具有相同的模型。然后，它会更新除第一个以外的所有型号，以便在型号名称后面显示序列号：

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;