C#销售管理系统用户权限控制

  3.2.1 用户登录
 主要代码如下：
private void button1_Click(object sender, EventArgs e)
        {
             OleDbDataReader MyyDataReader = MyFunction.GetOleDbDataReader("Select * From denglu WHERE power='" + this.comboBox1.Text.Trim() + "' and user='" + this.textBox1.Text.Trim() + "' and password='" + this.textBox2.Text.Trim() + "'");
            MyyDataReader.Read();
            if (MyyDataReader.HasRows)
            {
                str_power = this.comboBox1.Text.Trim();
                str_user = this.textBox1.Text.Trim();
                str_password = this.textBox2.Text.Trim();
                MainForm MyFormMain = new MainForm();
                this.Hide();
                //MyFormMain.Show();
        

            }
            else
            {
                MessageBox.Show("非法用户名或密码！", "出错提示信息", MessageBoxButtons.OK, MessageBoxIcon.Error);
                this.textBox2.Text = "";
                this.textBox1.Focus();
            
            }   MyyDataReader.Close();
            MyyDataReader.Dispose();
        }
3.2.2 用户注销
 部分代码：
private void MS_ExitItem_Click(object sender, EventArgs e)
        {