Update with predicate

[chrisrlong]

UPDATE
   T2
SET
   C1 =
      (
      SELECT
         C1
      FROM
         T1
      WHERE
         T1.C2 = T2.C2 AND
         T1.C3 = T2.C3
      )
WHERE
   EXISTS
      (
      SELECT
         1
      FROM
         T1
      WHERE
         T1.C2 = T2.C2 AND
         T1.C3 = T2.C3
      )

You may be able to directly update an in-line view as well. I'll leave that to someone else to show. I hate Oracle's implementation of that so bad that I never use it.

Welcome to Oracle

- Chris