$sth_mlg_addr_duplicate_check->execute(@fields[17,18,19,20,21,22,23])
      or warn "While checking for duplicate mailing address "
            . "$fields[17]; $fields[19] $fields[20]: "
            . $dbh->errstr;
              
($mlg_addr_id) = $sth_mlg_addr_duplicate_check->fetchrow_array();

my $mlg_id;
if(!defined($mlg_addr_id) && length($fields[20]) == 2) {

   #insert 
   $sth_insert_mlg_addr->execute(@fields[17,18,19,20,21,22,23])
      or warn "While inserting new mailing address "
            . "|$fields[17]|; |$fields[19]| |$fields[20]|, with id |$mlg_addr_id|: "
            . $dbh->errstr;

   #check duplicate
   $sth_mlg_addr_duplicate_check->execute(@fields[17,18,19,20,21,22,23])
      or warn "While checking for duplicate mailing address "
            . "|$fields[17]|; |$fields[19]| |$fields[20]|: "
            . $dbh->errstr;
            
   ($mlg_addr_id) = $sth_mlg_addr_duplicate_check->fetchrow_array();
   $mlg_id = $mlg_addr_id;
} else {
   $mlg_id = $mlg_addr_id;
}