What PL/SQL should I use?

Question

I need to:
1. Grab distinct combination of values from table A,
2. Check to see that I don't have those records in table B already
3. If a record exists in B, don't insert
4. If a record doesn't exist, insert.
What should I use? Sounds to me like a trigger job, but I read somewhere on the forum that triggers cannot check for dupes.
Table B's PK is a sys-generated value that I get out of a separate sequence/trigger.
Can someone, please give me direction?
Thanks,

Answer 1

I'm not sure why you'd need PL/SQL at all here... Seems like a pretty straightforward INSERT statement along the lines of
INSERT INTO b ( list_of_columns )
  SELECT list_of_columns
    FROM a
   WHERE NOT EXISTS(
      SELECT 1
        FROM b
       WHERE a.key = b.key )or
INSERT INTO b ( list_of_columns )
  SELECT list_of_columns
    FROM a
  MINUS
  SELECT list_of_columns
    FROM bDepending on your data (particularly the presence of NULLs), you may need to tweak this slightly, but it sounds like you can use a single SQL statement.
Justin