According to the value submitted by the form, the option value of the select drop-down box is selected by default:
<label>是否推荐：</label><select class="input-text" name="is_recommend">
<option value="0" <?php if($is_recommend=="0"){echo "selected";} ?> >不限</option>
<option value="1" <?php if($is_recommend=='1'){echo "selected";} ?> >是</option>
<option value="2" <?php if($is_recommend=='2'){echo "selected";} ?> >否</option></select>123456