ciao, ho il campo $data_nascita che vorrei rendere obbligatorio ma anche se lo compilo mi da il messaggio d'errore, come se non l'avessi compilato:

Codice PHP:
<?
                                        $data
=date("Y-m-d");
                                        
$giorno_sel=substr($row['data_nascita'],8,2);
                                        
$mese_sel=substr($row['data_nascita'],5,2);
                                        
$anno_sel=substr($row['data_nascita'],0,4);
                                        
?>
                                        <select name="gg1">
                                        <option value="">00</option>
                                        <?
                                        
for ($n=0;$n<=31;$n=$n+1){$n=sprintf("%02d",$n);
                                        
?>
                                        <option value=<?=$n?> <? if ($_POST["gg1"] == "$n") echo "SELECTED"?>><?=$n?></option>
                                        <? }?>
                                        </select>
                                        <select name="mm1">
                                        <option value="">00</option>
                                        <?
                                        
for ($n=0;$n<=12;$n=$n+1){$n=sprintf("%02d",$n);
                                        
?>
                                        <option value=<?=$n?> <? if ($_POST["mm1"] == "$n") echo "SELECTED"?>><?=$n?></option>
                                        <? }?>
                                        </select>
                                        <select name="aa1">
                                        <option value="">0000</option>
                                        <?
                                        
for ($n=1940;$n<=1998;$n=$n+1){$n=sprintf("%02d",$n);
                                        
?>
                                        <option value=<?=$n?> <? if ($_POST["aa1"] == "$n") echo "SELECTED"?>><?=$n?></option>
                                        <? }?>
                                        </select>    






$aa1."-".$mm1."-".$gg1 = $data_nascita;



if ($_POST["data_nascita"] != "") {

ok

else {

errore

}