C# + MySql exception: SELECT command denied to user ''@'localhost' for table *****

Question

I'm using C# + MySql + MySql connector to enter information into MySql database (via Xampp), And get the entered data back into a DataGridView.

When retrieving back the data, I get exceptions: (1) "SELECT command denied to user ''@'localhost' for table 'students'" and (2) "Host 'DELL-KL2001' is not allowed to connect to this MySQL server". The 2nd exception occurs when I run the code while connected to the Net. I tried similar question that being answered, though I'm not able to detect my coding error. Could you guys please look at my code and give a tip about the error in my code? Much appreciated.

P.S. I've not typed erroneous DB or table names like the case in some other questions I've read.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using MySql.Data.MySqlClient;

namespace MySqlBasics
{
public partial class FrmRegList : Form
{
    public FrmRegList()
    {
        InitializeComponent();
    }

    string MySqlConnectionString;

    private void FrmRegList_Load(object sender, EventArgs e)
    {
        string MySqlConnectionString = "Server=localhost;Database=student_reg.students;Uid=root;Pwd=pass";
    }

    private void btnEnter_Click(object sender, EventArgs e)
    {
        int mobileNo;
        string mobile = tbMobNo.Text;
        int.TryParse(mobile, out mobileNo);

        MySqlConnection sqlConnection = new MySqlConnection(MySqlConnectionString);
        MySqlCommand sqlCmd;
        sqlConnection.Open();

        try
        {
            sqlCmd = sqlConnection.CreateCommand();
            sqlCmd.CommandText = "INSERT INTO students(Id, Name, MobileNo)VALUES(@Id, @Name, @MobileNo)";
            sqlCmd.Parameters.AddWithValue("@Id", int.Parse(tbId.Text));
            sqlCmd.Parameters.AddWithValue("@Name", tbName);
            sqlCmd.Parameters.AddWithValue("@MobileNo", mobile);
            MySqlDataReader mySqlReader;
            mySqlReader = sqlCmd.ExecuteReader();
        }
        catch (Exception)
        {
            MessageBox.Show("Error: btnEnter_Click()");
        }

        LoadDataFromForm();
    }

    private void LoadDataFromForm()
    {
        MySqlConnection sqlConnection = new MySqlConnection(MySqlConnectionString);
        sqlConnection.Open();

        //try
        {
            MySqlCommand sqlCmd = sqlConnection.CreateCommand();
            sqlCmd.CommandText = "SELECT * FROM student_reg.students";

            MySqlDataAdapter sqlAdapter = new MySqlDataAdapter(sqlCmd);
            DataSet sqlDataset = new DataSet();
            sqlAdapter.Fill(sqlDataset);
            dGridRegs.DataSource = sqlDataset.Tables[0].DefaultView;
        }
        //catch (Exception ex)
        {
            //MessageBox.Show("Error: LoadDataFromForm() " + ex.Message);
        }
    }

    private void btnDebug_Click(object sender, EventArgs e)
    {
        LoadDataFromForm();
    }
}

}