PHP如何提取submit后的onclick计算的值，我要将值存入数据库

    <form method="post" action="jisuan.php?action=add">
    <input type="text" id="num1" name="num1"/>
      <table>
          <tr>
               <td>
                    <select id="op" name="sel">
                        <option value="+">+</option>
                        <option value="-">-</option>
                        <option value="*">*</option>
                        <option value="/">/</option>
                    </select>
              </td>      
        </tr>
    </table>
     <input type="text" id="num2" name="num2"/><br />
    <input type="submit" value="计算" onclick="calc()"/>
    <input type="button" value="查看" onclick="location.href='result.php'" /><br />
    </form>

calc设置你的表单控制值，服务端$_POST获取不就行了。。

 <form method="post" action="jisuan.php?action=add">
    <input type="text" id="num1" name="num1" />
    <table>
        <tr>
            <td>
                <select id="op" name="sel">
                    <option value="+">+</option>
                    <option value="-">-</option>
                    <option value="*">*</option>
                    <option value="/">/</option>
                </select>
            </td>
        </tr>
    </table>
    <input type="text" id="num2" name="num2" />=<input type="text" id="rst" name="rst" readonly="readonly" /><br />
    <input type="submit" value="计算" onclick="return calc()" />
    <input type="button" value="查看" onclick="location.href='result.php'" /><br />
</form>
<script>
    function calc() {
        var num1 = document.getElementById('num1'), num2 = document.getElementById('num2'), op = document.getElementById('op').value;
        if (num1.value == '') { alert('请输入num1'); return false; }
        if (num2.value == '') { alert('请输入num2'); return false; }
        num1 = parseFloat(num1.value) || 0;
        num2 = parseFloat(num2.value) || 0;
        if (op == '/' && num2 == 0) { alert('除数不能为0！');return false}

        document.getElementById('rst').value = eval(num1+op+num2);
    }
</script>

 $rst=$_POST["rst"];
///..........