增量更新插入...重复密钥

Question

有什么办法可以在mysql中的重复键更新插入增量更新吗？

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

NO，你就不能指定source = source + values(source);
因为源表blah没有在select包括，使用别名不会解决。

一种解决方法将使用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

Answer 2

如果你前缀表中列名，即blah.source，address_book.source？