สอบถามการใช้ list menu โดยฟังก์ชั่น Onchange ให้แสดงราคาสินค้าในแต่ละ ชนิดสินค้าทำอย่างไร

<table width="49%" border="1">
      <tr>
        <th width="20%" bgcolor="#00FF66" scope="col"><span class="style45">ชนิดสินค้า</span></th>
        <th colspan="2" bgcolor="#00FF66" scope="col"><span class="style45">รายละเอียดสินค้า</span></th>
        <th width="23%" bgcolor="#00FF66" scope="col"><span class="style45">ราคาสินค้า</span></th>
      </tr>
      <tr>
        <th bgcolor="#00FFFF" scope="row"><span class="style44">CD-ROM</span></th>
        <td colspan="2" bgcolor="#FFCCFF"><label for="select"></label>
          <div align="left">
				<select name="cdromid" id="cdromid" onchange ="this.form.textfield.value = this.value">
				  <option value="0">--โปรดเลือกรายการ--</option>
				  
				  <?php
	do {  
	?>
				  <option value="<?php echo $row_rsCdrom['Price']?>"><?php echo $row_rsCdrom['CdRom']?></option>
				  <?php
	} while ($row_rsCdrom = mysql_fetch_assoc($rsCdrom));
	  $rows = mysql_num_rows($rsCdrom);
	  if($rows > 0) {
		  mysql_data_seek($rsCdrom, 0);
		  $row_rsCdrom = mysql_fetch_assoc($rsCdrom);
	  }
	?>
				</select>
          </div></td>
        <td bgcolor="#FFFF00"><label for="textfield"></label>
          <div align="center">
            <input name="price1" type="text" id="textfield" size="18" />
          </div></td>
      </tr>
      <tr>
        <th bgcolor="#00FFFF" scope="row"><span class="style44">CPU</span></th>
        <td colspan="2" bgcolor="#FFCCFF"><label for="select"></label>
          <div align="left">
            <select name="cpuid" id="cpuid" >
              <option value="0">--โปรดเลือกรายการ--</option><?php
do {  
?><option value="<?php echo $row_rsCpu['CPU']?>"><?php echo $row_rsCpu['CPU']?></option>
              <?php
} while ($row_rsCpu = mysql_fetch_assoc($rsCpu));
  $rows = mysql_num_rows($rsCpu);
  if($rows > 0) {
      mysql_data_seek($rsCpu, 0);
	  $row_rsCpu = mysql_fetch_assoc($rsCpu);
  }
?>
            </select>
          </div></td>
        <td bgcolor="#FFFF00"><div align="center">
          <input name="price2" type="text" id="price2" size="18" />
        </div></td>
      </tr>
      <tr>
        <th bgcolor="#00FFFF" scope="row"><span class="style44">Harddisk</span></th>
        <td colspan="2" bgcolor="#FFCCFF"><label for="select"></label>
          <div align="left">
            <select name="harddiskid" id="harddiskid">
              <option value="0">--โปรดเลือกรายการ--</option>
              <?php
do {  
?><option value="<?php echo $row_rsHarddisk['HardDisk']?>"><?php echo $row_rsHarddisk['HardDisk']?></option>
              <?php
} while ($row_rsHarddisk = mysql_fetch_assoc($rsHarddisk));
  $rows = mysql_num_rows($rsHarddisk);
  if($rows > 0) {
      mysql_data_seek($rsHarddisk, 0);
	  $row_rsHarddisk = mysql_fetch_assoc($rsHarddisk);
  }
?>
            </select>
          </div></td>
        <td bgcolor="#FFFF00"><div align="center">
          <input name="price3" type="text" id="price3" size="18" />
        </div></td>
      </tr>
      <tr>
        <th bgcolor="#00FFFF" scope="row"><span class="style44">Mainboard</span></th>
        <td colspan="2" bgcolor="#FFCCFF"><label for="select"></label>
          <div align="left">
            <select name="mainboardid" id="mainboardid">
              <option value="0">--โปรดเลือกรายการ--</option>
              <?php
do {  
?><option value="<?php echo $row_rsMainboard['MainBoard']?>"><?php echo $row_rsMainboard['MainBoard']?></option>
              <?php
} while ($row_rsMainboard = mysql_fetch_assoc($rsMainboard));
  $rows = mysql_num_rows($rsMainboard);
  if($rows > 0) {
      mysql_data_seek($rsMainboard, 0);
	  $row_rsMainboard = mysql_fetch_assoc($rsMainboard);
  }
?>
            </select>
          </div></td>
        <td bgcolor="#FFFF00"><div align="center">
          <input name="price4" type="text" id="price4" size="18" />
        </div></td>
      </tr>
      <tr>
        <th bgcolor="#00FFFF" scope="row"><span class="style44">Monitor</span></th>
        <td colspan="2" bgcolor="#FFCCFF"><label for="select"></label>
          <div align="left">
            <select name="monitorid" id="monitorid">
              <option value="0">--โปรดเลือกรายการ--</option>
              <?php
do {  
?><option value="<?php echo $row_rsMonitor['Monitor']?>"><?php echo $row_rsMonitor['Monitor']?></option>
              <?php
} while ($row_rsMonitor = mysql_fetch_assoc($rsMonitor));
  $rows = mysql_num_rows($rsMonitor);
  if($rows > 0) {
      mysql_data_seek($rsMonitor, 0);
	  $row_rsMonitor = mysql_fetch_assoc($rsMonitor);
  }
?>
            </select>
          </div></td>
        <td bgcolor="#FFFF00"><div align="center">
          <input name="price5" type="text" id="price5" size="18" />
        </div></td>
      </tr>
      <tr>
        <th bgcolor="#00FFFF" scope="row"><span class="style44">NetworkCard</span></th>
        <td colspan="2" bgcolor="#FFCCFF"><label for="select"></label>
          <div align="left">
            <select name="networdcardid" id="networdcardid">
              <option value="0">--โปรดเลือกรายการ--</option>
              <?php
do {  
?><option value="<?php echo $row_rsNetworkcard['NetWorkCard']?>"><?php echo $row_rsNetworkcard['NetWorkCard']?></option>
              <?php
} while ($row_rsNetworkcard = mysql_fetch_assoc($rsNetworkcard));
  $rows = mysql_num_rows($rsNetworkcard);
  if($rows > 0) {
      mysql_data_seek($rsNetworkcard, 0);
	  $row_rsNetworkcard = mysql_fetch_assoc($rsNetworkcard);
  }
?>
            </select>
          </div></td>
        <td bgcolor="#FFFF00"><div align="center">
          <input name="price6" type="text" id="price6" size="18" />
        </div></td>
      </tr>
      <tr>
        <th bgcolor="#00FFFF" scope="row"><span class="style44">RAM</span></th>
        <td colspan="2" bgcolor="#FFCCFF"><label for="select"></label>
          <div align="left">
            <select name="ramid" id="ramid">
              <option value="0">--โปรดเลือกรายการ--</option>
              <?php
do {  
?><option value="<?php echo $row_rsRam['Ram']?>"><?php echo $row_rsRam['Ram']?></option>
              <?php
} while ($row_rsRam = mysql_fetch_assoc($rsRam));
  $rows = mysql_num_rows($rsRam);
  if($rows > 0) {
      mysql_data_seek($rsRam, 0);
	  $row_rsRam = mysql_fetch_assoc($rsRam);
  }
?>
            </select>
          </div></td>
        <td bgcolor="#FFFF00"><div align="center">
          <input name="price7" type="text" id="price7" size="18" />
        </div></td>
      </tr>
      <tr>
        <th bgcolor="#00FFFF" scope="row"><span class="style44">SoundCard</span></th>
        <td colspan="2" bgcolor="#FFCCFF"><label for="select"></label>
          <div align="left">
            <select name="soundcardid" id="soundcardid">
              <option value="0">--โปรดเลือกรายการ--</option>
              <?php
do {  
?><option value="<?php echo $row_rsSoundcard['SoundCard']?>"><?php echo $row_rsSoundcard['SoundCard']?></option>
              <?php
} while ($row_rsSoundcard = mysql_fetch_assoc($rsSoundcard));
  $rows = mysql_num_rows($rsSoundcard);
  if($rows > 0) {
      mysql_data_seek($rsSoundcard, 0);
	  $row_rsSoundcard = mysql_fetch_assoc($rsSoundcard);
  }
?>
            </select>
          </div></td>
        <td bgcolor="#FFFF00"><div align="center">
          <input name="price8" type="text" id="price8" size="18" />
        </div></td>
      </tr>
      <tr>
        <th bgcolor="#00FFFF" scope="row"><span class="style44">Speaker</span></th>
        <td colspan="2" bgcolor="#FFCCFF"><label for="select"></label>
          <div align="left">
            <select name="speakerid" id="speakerid">
              <option value="0">--โปรดเลือกรายการ--</option>
              <?php
do {  
?><option value="<?php echo $row_rsSpeaker['Speaker']?>"><?php echo $row_rsSpeaker['Speaker']?></option>
              <?php
} while ($row_rsSpeaker = mysql_fetch_assoc($rsSpeaker));
  $rows = mysql_num_rows($rsSpeaker);
  if($rows > 0) {
      mysql_data_seek($rsSpeaker, 0);
	  $row_rsSpeaker = mysql_fetch_assoc($rsSpeaker);
  }
?>
            </select>
          </div></td>
        <td bgcolor="#FFFF00"><div align="center">
          <input name="price9" type="text" id="price9" size="18" />
        </div></td>
      </tr>
      <tr>
        <th bgcolor="#00FFFF" scope="row"><span class="style44">VGA</span></th>
        <td colspan="2" bgcolor="#FFCCFF"><label for="select"></label>
          <div align="left">
            <label for="select"></label>
            <select name="vgaid" id="vgaid">
              <option value="0">--โปรดเลือกรายการ--</option>
              <?php
do {  
?><option value="<?php echo $row_rsVga['DisplayCard']?>"><?php echo $row_rsVga['DisplayCard']?></option>
              <?php
} while ($row_rsVga = mysql_fetch_assoc($rsVga));
  $rows = mysql_num_rows($rsVga);
  if($rows > 0) {
      mysql_data_seek($rsVga, 0);
	  $row_rsVga = mysql_fetch_assoc($rsVga);
  }
?>
            </select>
</div></td>
        <td bgcolor="#FFFF00"><label for="label"></label>
          <div align="center">
            <input name="price10" type="text" id="label" size="18" />
        </div></td>
      </tr>
      <tr>
        <th colspan="3" bgcolor="#CC9900" scope="row"><span class="style45">รวมราคาสินค้าที่เลือกทั้งหมด</span></th>
        <td bgcolor="#99FFFF"><label for="label2"></label>
          <div align="center">
            <input name="textfield11" type="text" id="label2" size="18" />
        </div></td>
      </tr>
      </table>