Well, that would work but I was thinking that you'd get the RE from Regexp::Assemble in a more direct way. Here's a complete, tested example:

#!/usr/bin/perl

use strict; use warnings;
use Regexp::Assemble;

open KEYS,"patterns" or die "Can't open the pattern file: $!";
my $exp = Regexp::Assemble ->new(flags => 'i',chomp => 1) ->add( <KEYS
+> );
close KEYS;

my $re = $exp->re;                      # store the assembled RE for l
+ater

while (my $text = <DATA>) {
   chomp($text);
   my @parts = split /(?=$re)/, $text;  # split based on stored RE
   for my $part (@parts) {
      print "line $.: $part\n";
   }
}
exit;

__DATA__
insert newtab values(1) drop table newtab
create table XXXX (field1 int null) insert XXXX values(1) grant select
+ on XXXX to sa drop table XXXX
create table XXXX (field1 int null) insert XXXX values(1) grant select
+ on XXXX to sa drop table XXXX rollback tran
create table XXXX (field1 int null) sp_help XXXX
insert XXXX values(1) grant select on XXXX to sa drop table XXXX rollb
+ack tran
lock table cDsnJbgnd..smfJwDlwb in share mode
[download]

I didn't write this earlier because I hadn't installed or read the docs to Regexp::Assemble yet. Also, I removed the /g flag that you passed to Regexp::Assemble->new as perl told me that it was a useless use.