Bootstrap表单布局样式

<form class="form-horizontal" role="form">
                    <fieldset>
                        <legend>配置数据源</legend>
                       <div class="form-group">
                          <label class="col-sm-2 control-label" for="ds_host">主机名</label>
                          <div class="col-sm-4">
                             <input class="form-control" id="ds_host" type="text" placeholder="192.168.1.161"/>
                          </div>
                          <label class="col-sm-2 control-label" for="ds_name">数据库名</label>
                          <div class="col-sm-4">
                             <input class="form-control" id="ds_name" type="text" placeholder="msh"/>
                          </div>
                       </div>
                       <div class="form-group">
                          <label class="col-sm-2 control-label" for="ds_username">用户名</label>
                          <div class="col-sm-4">
                             <input class="form-control" id="ds_username" type="text" placeholder="root"/>
                          </div>
                          <label class="col-sm-2 control-label" for="ds_password">密码</label>
                          <div class="col-sm-4">
                             <input class="form-control" id="ds_password" type="password" placeholder="123456"/>
                          </div>
                       </div>
                    </fieldset>     
                    <fieldset>
                         <legend>选择相关表</legend>
                        <div class="form-group">
                           <label for="disabledSelect"  class="col-sm-2 control-label">表名</label>
                           <div class="col-sm-10">
                              <select id="disabledSelect" class="form-control">
                                 <option>禁止选择</option>
                                 <option>禁止选择</option>
                              </select>
                           </div>
                        </div>
                    </fieldset>
                    
                       <fieldset>
                         <legend>字段名</legend>
                        <div class="form-group">
                           <label for="disabledSelect"  class="col-sm-2 control-label">表名</label>
                           <div class="col-sm-10">
                              <select id="disabledSelect" class="form-control">
                                 <option>禁止选择</option>
                                 <option>禁止选择</option>
                              </select>
                           </div>
                        </div>
                    </fieldset>
                </form>

                  <div class="form-group">
                   <label for="ds_name"  class="col-sm-2 control-label">表名</label>
                   <div class="col-sm-4">
                      <select id="disabledSelect" class="form-control">
                         <option>禁止选择</option>
                         <option>禁止选择</option>
                      </select>
                   </div>
                </div>