Combobox en condicion de otro

[sergiosuarezmartin]

Hola. Llevo un tiempo pasandome por la web mirando cositas y ahora que necesito algo de ayuda pues a ver si me sabeis decir.

Tengo el siguiente codigo, en el que tengo dos combobox, quiero que dependiendo lo que se seleccione en el primero, en el segundo me recarge de bbdd lo correspondiente al primero.

el tema es el siguiente:
Insertas una categoria.
seleccionas si es nueva, o ya existente; si es nueva, la escribes en el textbox, de lo contrario, aparece el combobox con las categorias de productos que tengo.
dependiendo de si has seleccionado NUEVA, o YA EXISTENTE, el combobox se recargará con todas las subcategorias, o con las categorias de esa categoria seleccionada.

Código PHP:

 <form method="post" action="insertarcategoria.php" name="categoria"><table width="100%" height="160" border="0" cellpadding="0" cellspacing="0"> 
                                    <tr> 
                                      <td width="42%"><span class="inicialLetra">N</span><span class="LetraMenuBuscar">ombre</span> <span class="inicialLetra">C</span><span class="LetraMenuBuscar">ategor&iacute;a:</span></td> 
                                      <td width="28%" align="center"><label> 
                                        <input name="catego" type="text" class="CajaTexto2" size="13" /> 
                                      </label></td> 
                                      <td width="30%" align="center"><label> 
                                       
                                      <? 
                                       
                          $sql_sacar="select * from categoria"; 
                         $consulta=mysql_query($sql_sacar, $connect); 
                         
                         if($array=mysql_fetch_array($consulta)){ 
                         
                          
                                      echo "<select name='combocat'>"; 
                                     
                                      do { 
                                            echo " <option value= '" .$array['id_cat']."'>" .$array['nom_cat']."</option>";     
                                        } 
                                        while ($array = mysql_fetch_array($consulta)); 
                                        $codigo=$array['id_cat']; 
                                        echo  "</select>"; 
                                        } 
                                        ?> 
                                 
                                      </label></td> 
                                    </tr> 
                                    <tr> 
                                      <td>Nueva:<input type="radio" name="rad" checked="checked" onclick="mostrar(this.form,0)" />   
                                      Ya existente 
                                        <input type="radio" name="rad" onclick="mostrar(this.form,1)" /></td> 
                                      <td align="center"></td> 
                                      <td align="center"><label> 
                                       
                                       
                                       
 
                                         
                                         
 
                                      </label></td> 
                                    </tr> 
                                    <tr> 
                                      <td height="21" colspan="3">&iquest;Desea introducir una subcategor&iacute;a para la categor&iacute;a creada? 
                                        <a href="javascript:mostrarOcultarTablas('tabla1')">SI</a> 
                                        
                                       <a href="javascript:mostrarOcultarTablas('tabla1')">NO</a></td> 
                                      </tr> 
                                    <tr> 
                                      <td height="22" colspan="3" ><div id="tabla1" style="display: none"><table width="100%" border="0" cellspacing="0" cellpadding="0" name="subcategorias"> 
                                        <tr> 
                                          <td width="42%"><span class="inicialLetra">S</span><span class="LetraMenuBuscar">ubcategor&iacute;a:</span></td> 
                                          <td width="29%" align="center"><input name="subcatego" type="text" class="CajaTexto2" size="13" /></td> 
                                          <td width="29%" align="center"> 
                                           
                                          <?   
                                 
                                      if(isset($rad)) 
                                      { 
                          $sql_sacar2="select * from subcategoria"; 
                         $consulta2=mysql_query($sql_sacar2, $connect); 
                         
                         if($array2=mysql_fetch_array($consulta2)){ 
                         
                          
                                      echo "<select name='combosub'>"; 
                                      
                                      do { 
                                            echo " <option value= '" .$array2['id_sub']."'>" .$array2['nom_subcat']."</option>"; 
                                        }while ($array2 = mysql_fetch_array($consulta2)); 
                                        echo  "</select>"; 
                                        } 
                                        } 
                                         
                                        else 
                                        { 
                                         $sql_sacar2="select * from subcategoria where id_cat='$codigo'"; 
                         $consulta2=mysql_query($sql_sacar2, $connect); 
                         
                         if($array2=mysql_fetch_array($consulta2)){ 
                         
                          
                                      echo "<select name='combosub'>"; 
                                      
                                      do { 
                                            echo " <option value= '" .$array2['id_sub']."'>" .$array2['nom_subcat']."</option>"; 
                                        }while ($array2 = mysql_fetch_array($consulta2)); 
                                        echo  "</select>"; 
                                        } 
                                         
                                         
                                        } 
                                        ?></td> 
                                        </tr> 
                                        <tr> 
                                          <td>Nueva:<input type="radio" name="rad3" checked="checked" onclick="mostrar3(this.form,0)" />   
                                      Ya existente 
                                        <input type="radio" name="rad3" onclick="mostrar3(this.form,1)" /></td> 
                                          <td>&nbsp;</td> 
                                          <td>&nbsp;</td> 
                                        </tr> 
                                      </table></div></td> 
                                    </tr> 
                                    <tr> 
                                      <td>&nbsp;</td> 
                                      <td>&nbsp;</td> 
                                      <td align="center"><input type="image" border="0" name="imageField34" src="Img/btn_go.gif" /></td> 
                                    </tr> 
                                     
                                  </table> 
                                  </form>  

inserto una foto para que veais como es el concepto

[hackjose]

Segun lo que yo entiendo.
Se llaman select dependientes

aqi ay un muy buen ejemplo

http://www.formatoweb.com.ar/ajax/se...pendientes.php

[sergiosuarezmartin]

muuchas gracias!! solucionado! :P