open( FILE, $filename )  
   or die " Can't open file ($filename):  $!\n";

while ( my $line = <FILE> ) {

   chomp $line;

   my @fields = split( /\t/, $line );

   ### do some added parsing, then insert
}

##</code><code>##

## outside the loop
my @firstLines = qw/ AccessInstr PropType UID Acres MLSNum MediaSource /;
my %firsts = map { $_ => 1 } @firstLines;

## the loop 
while ( my $line = <FILE> ) {

   chomp $line;

   my @fields = split( /\t/, $line );

   my $lines = 0;
   if ( $firsts{$fields[0]} ) {
      %lookup = map { $lines++ => $_ } @fields;
      @dbFields = values %lookup;
   }

   %reversed = reverse %lookup;
   $mlsField = $reversed{'MLSNum'};
   $mlsNumber = $fields[$mlsField];

   $officeListField = $reversed{'OfficeList'};
   my $officeList = $fields[$officeListField];

   $officeSellField = $reversed{'OfficeSell'};
   my $officeSell = $fields[$officeSellField];

   next if ( $firsts{$fields[0]} );

   while ( scalar( @fields ) != scalar( @dbFields ) ) {
      push ( @fields, undef );
   }

   $testSth->execute( $mlsNumber );
   my $inDB = $testSth->fetchrow();

   $jbgTestSth->execute( $mlsNumber );
   my $inJBGDB = $jbgTestSth->fetchrow();

   my @updateVals ;
   if ( $inDB ) {
      my $i = 0;
      foreach my $loop ( @fields ) {
         push( @updateVals, $loop ) unless $i == $mlsField;
         $i++;
      }

      push( @updateVals, $mlsNumber );
      $updSth->execute( @updateVals );

   } else {
      $insSth->execute( @fields ) 
          unless ( $fields[$mlsField] eq '' );

   }

   if ( ( $officeList && grep( /$officeList/, @offices ) ) 
     or ( $officeSell && grep( /$officeSell/, @offices ) ) ) {
      if ( $inJBGDB ) {
         $updSummary->execute( @updateVals ) 
           or warn "no update! : " . $dbh->errstr();
      } else {
         $insSummary->execute( @fields )
      }
   }

}