I gather that you have a DB table designed without any unique keys and you are trying to add the keys after the fact with an update. My suggestion is that you dump all the table data out to a file, create a new table with a primary key attribute for ID, combine the data with the sequential ID's using a script, and then populate the table with the new data.

Update: You could also do it by inserting into a new table with values from the old one, like this:

use strict;
use warnings;
use DBI;
 
# Set up database connection
my $user = "content";
my $pass = "content";
 
 
my $dbh = DBI->connect("DBI:ODBC:LocalServer",$user, $pass, {RaiseErro
+r => 1});
 
my $new_id = 0;
 
# Assumes the new table request2 has the same layout as the first one.
# The ID should be declared as a primary key for this table.
# I assume it was not declared that way in table request.
my $sth = $dbh->prepare(q{SELECT * FROM request});
 
# There should be a placeholder for each value in the table.
my $sth2 = $dbh->prepare(q{INSERT INTO request2 VALUES(?,?,?)});
 
my $sql_data = ($sth->execute() || die $sth->errstr);
 
while (my $pointer = $sth->fetchrow_arrayref) {
   # Assumes the ID field is the first field.
   $pointer->[0] = $new_id;
   $sth2->execute(@{$pointer});
   $new_id++;
}
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In summary, it was a bad mistake to define an SQL table without unique keys, and the best way to recover is by getting the data into a new table.