use DBI;

my $dbh = DBI->connect( "DBI:mysql:database=test;host=localhost",
  "username", "password" );

my $sth = $dbh->prepare( 'select * from table_foo' );

$sth->execute();

my $numrecords = $sth->rows;

my $numfields = $sth->{'NUM_OF_FIELDS'};

$sth->finish;

print "I found $numrecords records, each having $numfields fields.\n";