新手 求问 vs 2012 win10系统 combox下拉组件问题

         ![图片说明](https://img-ask.csdn.net/upload/201704/20/1492697492_123209.png)    

                            用到的下拉框时，数据写死的话，注册窗口显示正常。
                            但是写成从数据库取出的数据时，注册窗口分辨率就变小了。


        ![图片说明](https://img-ask.csdn.net/upload/201704/20/1492697641_724987.png)                    

    正常情况。


    ![图片说明](https://img-ask.csdn.net/upload/201704/20/1492697682_549513.png)

    异常情况。

    下面是取值代码。



                            string sql1 = "SELECT * FROM nj_table";
            DataTable dt1 = conn.ExecuteDataTable(sql1);
            comboBox_nj.DataSource = dt1;
            comboBox_nj.DisplayMember = "njmc";
            comboBox_nj.ValueMember = "njID";

            int njID = (int)comboBox_nj.SelectedValue;
            string sql2 = "SELECT * FROM bj_table where njID="+njID;
            DataTable dt2 = conn.ExecuteDataTable(sql2);
            comboBox_bj.DataSource = dt2;
            comboBox_bj.DisplayMember = "bjmc";
            comboBox_bj.ValueMember = "bjID";

看读取的数据是否一致。。。然后在填充ComboBox。