jquery, le select option in table td, rilevo solo la prima....

[marcopa]

AVREI una soluzione, ma e' jscript non jquery, vorrei gestirla in jquery per poter aggiornare il db con una chiamata ajax, qualcuno saprebbe convertirla in jquery?
questa e' la modifica in jscript

<tr>
		 		        <td>
                        <select class="cambio" id="alfa" onchange="javascript: Visualizza(this.options[this.selectedIndex].value)"> 
                        	<option id="1" value="1">1</option>
                        	<option id="2" value="2">2</option>
                        	<option id="3" value="3">3</option>
                        	<option id="4" value="4">4</option>
                        	<option id="5" value="5">5</option>
                        </select>
                        </td>
					    <td>tecnologia 2</td>
					    <td>matricola  2</td>
					  </tr>
					<tr>
		 		        <td>
                        <select class="cambio" id="beta" onchange="javascript: Visualizza(this.options[this.selectedIndex].value)">  
                        	<option id="A" value="A">A</option>
                        	<option id="B" value="B">B</option>
                        	<option id="C" value="C">C</option>
                        	<option id="D" value="D">D</option>
                        	<option id="E" value="E">E</option>
                        </select>
                        </td>
					    <td>tecnologia  3</td>
					    <td>matricola 3</td>
					  </tr>
					<tr>
		 		        <td>
                        <select class="cambio" id="gamma" onchange="javascript: Visualizza(this.options[this.selectedIndex].value)">  
                        	<option id="10" value="10">10</option>
                        	<option id="20" value="20">20</option>
                        	<option id="30" value="30">30</option>
                        	<option id="40" value="40">40</option>
                        	<option id="50" value="50">50</option>
                        </select>
                        </td>
					    <td>tecnologia </td>
					    <td>matricola </td>
					  </tr>

questa e' la parte jscript

<script language="javascript">
function Visualizza(valore)
{
    alert(valore)
}
</script>