my $dbh = DBI->connect($dsn, $user, $password,
             { RaiseError => 1, AutoCommit => 0 });

# do SQL's that forms the transaction
my $sth = $dbh->prepare(...)
$sth->execute;
$dbh->do(...);

# commit the transaction
$dbh->do( "COMMIT" );

##</code><code>##

LOCK TABLES table1 WRITE, table2 WRITE

INSERT INTO table1 SELECT * FROM table2;

UNLOCK TABLES