求高手帮忙指点指点（本人菜鸟）

private void button1_Click(object sender, EventArgs e)
        {

            Form2 form2_01 = new Form2();
            OleDbConnection aConnection = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Application.StartupPath + "/" + "DB.mdb");
            aConnection.Open();///打开数据库
            string SQLString = "select * from user where name=" + textBox1.Text.Trim() + " and password="+textBox2.Text.Trim ();///设置sql 查询语句
            OleDbDataAdapter myadapter = new OleDbDataAdapter(SQLString, aConnection); ///创建适配器，执行sql 查询
            DataSet ds = new DataSet(); ///建立数据集
            myadapter.Fill(ds); ///将查询结果加入 ds 中
            if (ds.Tables[0].Rows.Count > 0) ///判断用名密码是否正确
            {
                OleDbDataAdapter qx_adapter = new OleDbDataAdapter("select qx from user where name=" + textBox1.Text.Trim() , aConnection);
                DataSet ds_qx = new DataSet();
                qx_adapter.Fill(ds_qx);
                qx = Convert.ToInt32(ds_qx.Tables[0].Rows[0]["qx"]);
                this.Hide();
                form2_01 form2 = new form2_01(qx);
                form2.Show();
            }
            else
            {
                ///MessageBox.Show("你按了确定");
                MessageBox.Show("对不起，请输入正确的用户名和密码");
            }
            aConnection.Close();///关闭数据库连接（必须）
        }

        private int i = 0;
        public form2_01(int qx)
        {
            InitializeComponent();
            this.i = qx;
        }