Question

quite the same question as here : Copy data from one existing row to another existing row in SQL?

but in Oracle, where update ... from and update t1, t2 are not supported.

I’ll repeat it here in my own words ;
I have a table T, which looks like this :

and as the arrow shows it, I want to copy everything from r where c = 1 to e where c = 2, with t matching.

I have the select statement to get what I want to copy :

select 
  told.t, 
  told.r
from 
  T told 
  inner join 
  T tnew
on 
  told.t= tnew.t
where 
  told.c = 1
  and 
  tnew.c = 2

I just don’t know how to put this together in an update. An Oracle update, specifically.

Answer 1

try this:

update T tnew
set tnew.e = (select told.r from T told where told.c = 2 and told.t = tnew.t)
where tnew.c = 1