VB.NET/C# MySQL (ADO.NET) พื้นฐานการ เขียนโปรแกรม ADO.NET เชื่อมต่อกับฐานข้อมูล MySQL

CREATE TABLE `member` (
  `CustomerID` varchar(4) NOT NULL,
  `Username` varchar(30) NOT NULL,
  `Password` varchar(30) NOT NULL,
  `Name` varchar(50) NOT NULL,
  `Email` varchar(50) NOT NULL,
  `CountryCode` varchar(2) NOT NULL,
  `Budget` double NOT NULL,
  `Used` double NOT NULL,
  PRIMARY KEY  (`CustomerID`),
  UNIQUE KEY `Email` (`Email`),
  KEY `CountryCode` (`CountryCode`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

-- 
-- Dumping data for table `member`
-- 

INSERT INTO `member` VALUES ('C001', 'win', 'win123', 'Win Weerachai', '[email protected]', 'TH', 1000000, 600000);
INSERT INTO `member` VALUES ('C002', 'john', 'john123', 'John  Smith', '[email protected]', 'EN', 2000000, 800000);
INSERT INTO `member` VALUES ('C003', 'jame', 'jame123', 'Jame Born', '[email protected]', 'US', 3000000, 600000);
INSERT INTO `member` VALUES ('C004', 'chalee', 'chalee123', 'Chalee Angel', '[email protected]', 'US', 4000000, 100000);

Imports MySql.Data.MySqlClient
Imports System.Data
Public Class frmLogin

    Private Sub btnLogin_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLogin.Click

        Dim objConn As New MySqlConnection
        Dim objCmd As New MySqlCommand
        Dim strConnString, strSQL As String

        strConnString = "Server=localhost;User Id=root; Password=root; Database=database; Pooling=false"
        objConn.ConnectionString = strConnString
        objConn.Open()

        Dim intNumRows As Integer
        strSQL = "SELECT COUNT(*) FROM member WHERE Username = '" & Me.txtUsername.Text & "' AND Password = '" & Me.txtPassword.Text & "' "
        objCmd = New MySqlCommand(strSQL, objConn)
        intNumRows = objCmd.ExecuteScalar()

        If intNumRows > 0 Then
            Dim frm As New frmMain
            frm._strUser = Me.txtUsername.Text
            frm.LoadInfor()
            frm.Show()

            Me.Hide()
        Else
            MessageBox.Show("Username or Password Incorrect")
        End If

        objConn.Close()
        objConn = Nothing

    End Sub

    Private Sub btnClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClose.Click
        If MessageBox.Show("Exit application?", "", MessageBoxButtons.YesNo) = DialogResult.Yes Then
            Application.Exit()
        End If
    End Sub


End Class

Imports MySql.Data.MySqlClient
Imports System.Data


Public Class frmMain

    Dim strUser As String

    Public Property _strUser() As String
        Get
            Return strUser
        End Get
        Set(ByVal value As String)
            strUser = value
        End Set
    End Property

    Public Sub LoadInfor()

        Dim objConn As New MySqlConnection
        Dim objCmd As New MySqlCommand
        Dim dtAdapter As MySqlDataAdapter
        Dim dt As New DataTable
        Dim strConnString, strSQL As String

        strConnString = "Server=localhost;User Id=root; Password=root; Database=database; Pooling=false"
        objConn.ConnectionString = strConnString
        objConn.Open()

        strSQL = "SELECT * FROM member WHERE Username = '" & strUser & "' "

        dtAdapter = New MySqlDataAdapter(strSQL, objConn)
        dtAdapter.Fill(dt)

        If dt.Rows.Count > 0 Then
            Me.lblUser.Text = strUser
            Me.lblName.Text = dt.Rows(0)("Name")
            Me.lblEmail.Text = dt.Rows(0)("Email")
        End If

        objConn.Close()
        objConn = Nothing
    End Sub

    Private Sub btnBack_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnBack.Click
        Dim frm As New frmLogin
        frm.Show()

        Me.Hide()
    End Sub
End Class

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

namespace LoginFormCS
{
    public partial class frmLogin : Form
    {
        public frmLogin()
        {
            InitializeComponent();
        }

        private void btnLogin_Click(object sender, EventArgs e)
        {
            MySqlConnection objConn = new MySqlConnection();
            MySqlCommand objCmd = new MySqlCommand();
            string strConnString = null;
            string strSQL = null;

            strConnString = "Server=localhost;User Id=root; Password=root; Database=database; Pooling=false";
            objConn.ConnectionString = strConnString;
            objConn.Open();

            int intNumRows = 0;
            strSQL = "SELECT COUNT(*) FROM member WHERE Username = '" + this.txtUsername.Text + "' AND Password = '" + this.txtPassword.Text + "' ";
            objCmd = new MySqlCommand(strSQL, objConn);
            intNumRows = Convert.ToInt32(objCmd.ExecuteScalar());

            if (intNumRows > 0)
            {
                frmMain frm = new frmMain();
                frm._strUser = this.txtUsername.Text;
                frm.LoadInfor();
                frm.Show();

                this.Hide();
            }
            else
            {
                MessageBox.Show("Username or Password Incorrect");
            }

            objConn.Close();
            objConn = null;
        }

        private void btnClose_Click(object sender, EventArgs e)
        {
            if (MessageBox.Show("Exit application?", "", MessageBoxButtons.YesNo) == DialogResult.Yes)
            {
                Application.Exit();
            }
        }


    }
}

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

namespace LoginFormCS
{


    public partial class frmMain : Form
    {
        public frmMain()
        {
            InitializeComponent();
        }

        string strUser;
        public string _strUser
        {
            get { return strUser; }
            set { strUser = value; }
        }

        public void LoadInfor()
        {
            MySqlConnection objConn = new MySqlConnection();
            MySqlCommand objCmd = new MySqlCommand();
            MySqlDataAdapter dtAdapter = default(MySqlDataAdapter);
            DataTable dt = new DataTable();
            string strConnString = null;
            string strSQL = null;

            strConnString = "Server=localhost;User Id=root; Password=root; Database=database; Pooling=false";
            objConn.ConnectionString = strConnString;
            objConn.Open();

            strSQL = "SELECT * FROM member WHERE Username = '" + strUser + "' ";

            dtAdapter = new MySqlDataAdapter(strSQL, objConn);
            dtAdapter.Fill(dt);

            if (dt.Rows.Count > 0)
            {
                this.lblUser.Text = strUser;
                this.lblName.Text = dt.Rows[0]["Name"].ToString();
                this.lblEmail.Text = dt.Rows[0]["Email"].ToString();
            }

            objConn.Close();
            objConn = null;
        }

        private void btnBack_Click(object sender, EventArgs e)
        {
        frmLogin frm = new frmLogin();
        frm.Show();
        this.Hide();
        }
    }
}