C#登录代码不起作用

我正在尝试使用跨表参数化SQL创建登录代码。代码不起作用，我不知道为什么

C#代码：

我希望它能让学生或老师（不同的用户）使用正确的用户名和密码进行访问。但是，我一直得到相同的输出：

用户名或密码不正确。请再试一次

MySql.Data.dll中发生类型为“System.IndexOutOfRangeException”的未处理异常

其他信息：在结果中找不到指定列：teacher.username

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也许您必须在sql查询中使用或条件？

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如果我想编辑代码，以便：如果教师登录-发送教师到教师表单。否则，如果学生登录-将学生发送到学生表单？在DBReader.Read（）中读取登录名和密码，并用我不太熟悉的c#代码再次验证。请阅读。你能给我一个示例代码让我开始吗？应该是这样的while（DBReader.Read（））{var teacherLogin=DBReader.GetString（“数据库中的列的名称”）；var teacherPass=DBReader.GetString（“数据库中的列的名称”）；如果（teacherLogin==yourLogin&&teacherPass==yourPass）{//it is teacher}//为普通用户添加相同的逻辑}我是否需要指定表，因为列名称“username”同时在教师和学生中

    using (MySqlConnection connection = new MySqlConnection("datasource=localhost;port=3306;database=project;username=root;password=***;"))
{
    MySqlCommand cmd = new MySqlCommand(@"SELECT  * FROM student, teacher 
     WHERE student.username = @userName AND student.password = @passWord 
     AND teacher.username = @teacherUser AND teacher.password = @teacherPass;");

    cmd.CommandType = CommandType.Text;
    cmd.Connection = connection;
    cmd.Parameters.AddWithValue("@userName", textboxUsername.Text);
    cmd.Parameters.AddWithValue("@passWord", texBoxPassword.Text);
    cmd.Parameters.AddWithValue("@teacherUser", textBoxTeacherUsername.Text);
    cmd.Parameters.AddWithValue("@teacherPass", textBoxTeacherPassword.Text);
    connection.Open();    
    MySqlDataReader DBReader;
    DBReader = cmd.ExecuteReader();
    cmd.Connection = connection;
    int check = 0;
    while (DBReader.Read())
    {
        check = check + 1;
    }
    if (check == 1)
    {
        MessageBox.Show(" Login Successfull");
        this.Hide();
        Test ss = new Test();
        ss.Show();
    }
    else
    {
         MessageBox.Show("Username or Password Incorrect.  Try Again please");
    }
    connection.Close();

}

     MySqlCommand cmd = new MySqlCommand("SELECT * FROM student, teacher WHERE (student.username = @userName AND student.password = @passWord) OR (teacher.username = @teacherUser AND teacher.password = @teacherPass);");
            cmd.CommandType = CommandType.Text;
            cmd.Connection = connection;
            cmd.Parameters.AddWithValue("@userName", textboxUsername.Text);
            cmd.Parameters.AddWithValue("@passWord", texBoxPassword.Text);
            cmd.Parameters.AddWithValue("@teacherUser", textboxUsername.Text);
            cmd.Parameters.AddWithValue("@teacherPass", texBoxPassword.Text);
            connection.Open();
            MySqlDataReader DBReader;
            cmd.Connection = connection;
            DBReader = cmd.ExecuteReader();
            int check = 0;
            while (DBReader.Read())
            {
                var teacherLogin = DBReader.GetString("teacher.username");
                var teacherPass = DBReader.GetString("teacher.password");
                var studentLogin = DBReader.GetString("student.username");
                var studentPass = DBReader.GetString("student.password");

                if (teacherLogin == textboxUsername.Text && teacherPass == texBoxPassword.Text)
                {
                    MessageBox.Show("Login Successfull!");

                    this.Hide();
                    Registration ss = new Registration();
                    ss.Show();
                }
                else if (studentLogin == texBoxPassword.Text && studentPass == texBoxPassword.Text)
                {
                    MessageBox.Show(" Login Successfull");

                    this.Hide();
                    Test ss = new Test();
                    ss.Show();
                }
                else
                {
                    MessageBox.Show("Username or Password Incorrect.  Try Again please");
                }

            }

SELECT * FROM student, teacher WHERE (student.username = @userName AND student.password = @passWord) OR (teacher.username = @teacherUser AND teacher.password = @teacherPass)