Question

有没有办法在mysql中的重复密钥更新插入中进行增量更新？

示例w /错误：

insert into blah (user_id, prefix, email_id, field, source) 
select user_id, substring(name, 1, 3), contact_email_id, 2, source from address_book 
on duplicate key update source = source + values(source);

ERROR 1052 (23000): Column 'source' in field list is ambiguous

Answer 1

如果您将表前缀添加到列名称，即blah.source，address_book.source？

，该怎么办？

Answer 2

否，您无法指定source = source + values(source);
因为源表blah未包含在select中，使用别名无法解决。

解决方法将使用left join

insert into blah (user_id, prefix, email_id, field, source) 
select 
  ab1.user_id, substring(ab1.name, 1, 3), ab1.contact_email_id, 2, 
  if(ab2.source, ab1.source+ab2.source, ab1.source)
from 
  address_book ab1
left join
  blah1 as ab2
on 
  ab1.user_id=ab2.user_id
on duplicate key 
update source = values(source); 
/* values(source) = ab1.source+ab2.source if duplicate found */

谨防1:N关系

insert ... on duplicate key上的增量更新

2 个答案: