eval {
     #table A
     foreach line (...) {
           prepare, execute
     }
    
     #table B
     prepare, execute 
}
if ( $@ ) {
    rollback
}
else {
    commit;
}

##</code><code>##

my $dbh = DBI->connect('DBI:MSSQL:database', {AutoCommit => 0}, )
   or die "Couldn't connect to database: " . DBI->errstr;