use DBI;

my $dbh = DBI->connect("dbi:SQLite:dbname=test.db","","") or die DBI::errstr;

my $sql = "SELECT ID, Vegetarisch FROM Buchungen WHERE Datum = '".datum()."';";
my $sth = $dbh->prepare($sql);
$sth->execute;

my $anzahl_rows = $sth->rows;
print $anzahl_rows;