incremental update in insert ... on duplicate key

Question

Is there any way to do an incremental update in an on duplicate key update insert in mysql?

Example w/ error:

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, you just cannot specify source = source + values(source);
because source table blah is not included in the select, using alias won't fix.

A workaround will be using 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 */

beware on 1:N relation