Oracle-L: RE: PL/SQL Question:Eliminate duplicate rows

From: Igor Neyman <ineyman_at_perceptron.com>
Date: Fri, 19 Sep 2003 12:49:48 -0800
Message-ID: <F001.005D0863.20030919124948@fatcity.com>

Check SQL Reference for "exception_clause" when creating Primary Key. Could help to do what you need just using SQL (no PL/SQL).

Igor Neyman, OCP DBA
ineyman_at_perceptron.com

-----Original Message-----
Mercadante, Thomas F
Sent: Friday, September 19, 2003 2:55 PM To: Multiple recipients of list ORACLE-L

Johann,

how about the following. what this does is, using the inner begin/end block, catches when an insert would fail because of the PK failure and ignores the error.

This is very quick and dirty - it will work fine if you are not working with
a huge amount of data.

declare

cursor c1 is
  select col1, col2
   from some_table;
begin
for c1_rec in c1 loop
  begin
    insert into new_table(col1, col2)
      values (c1_rec.col1, c1_rec.col2);     exception

      when too_many_rows then
           null;

end;
end loop;
end;
/

If you are talking about lots and lots of data, you could easily query the
table you are inserting into, testing for the existence of the value you are
attempting to insert. If you find it, skip the insert. Like this:

declare
rec_count number;
cursor c1 is
  select col1, col2
   from some_table;
begin
for c1_rec in c1 loop
  begin
    select count(*)

     into rec_count
     from new_table
     where col1 = c1_rec.col1;  -- this assumes that col1 is the pk!
     if rec_count = 0 then
       insert into new_table(col1, col2)
        values (c1_rec.col1, c1_rec.col2);
     end if;
    exception
      when too_many_rows then
           null;

end;
end loop;
end;
/

Good Luck!

Tom Mercadante
Oracle Certified Professional

-----Original Message-----
Sent: Friday, September 19, 2003 3:05 PM To: Multiple recipients of list ORACLE-L

Looking for an a sample cursor routine to load a PK enabled table to eliminate
any dupes from the load table.

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Author: Igor Neyman
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