select表单添加可选与不可选的表单项代码

<select name="" id="">
<option value="">请选择</option>
<optgroup label="标题1" title="">
<option value="" title="">选项1-1</option>
<option value="" title="">选项2-2</option>
</optgroup>
<optgroup label="标题2" title="">
<option value="armscii8_bin" title="">选项2-1</option>
<option value="armscii8_general_ci" title="">选项2-1</option>
</optgroup>
</select>