VB.NET/C# Connect to SQL Server Using ADO.NET พื้นฐานกับ SQL Server and ADO.NET

USE [mydatabase]
GO
/****** Object:  Table [dbo].[member]    Script Date: 03/12/2012 09:27:14 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[member](
	[CustomerID] [varchar](4) NOT NULL,
	[Username] [varchar](30) NULL,
	[Password] [varchar](30) NULL,
	[Name] [varchar](50) NULL,
	[Email] [varchar](50) NULL,
	[CountryCode] [varchar](2) NULL,
	[Budget] [float] NULL,
	[Used] [float] NULL,
 CONSTRAINT [PK_customer] PRIMARY KEY CLUSTERED 
(
	[CustomerID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

GO
SET ANSI_PADDING OFF

/*-- Data */

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

Imports System.Data.SqlClient
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 SqlConnection
        Dim objCmd As New SqlCommand
        Dim strConnString, strSQL As String

        strConnString = "Server=localhost;UID=sa;PASSWORD=;Database=mydatabase;Max Pool Size=400;Connect Timeout=600;"
        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 SqlCommand(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 System.Data.SqlClient
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 SqlConnection
        Dim objCmd As New SqlCommand
        Dim dtAdapter As SqlDataAdapter
        Dim dt As New DataTable
        Dim strConnString, strSQL As String

        strConnString = "Server=localhost;UID=sa;PASSWORD=;Database=mydatabase;Max Pool Size=400;Connect Timeout=600;"
        objConn.ConnectionString = strConnString
        objConn.Open()

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

        dtAdapter = New SqlDataAdapter(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 System.Data.SqlClient;
using System.IO;

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

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

            strConnString = "Server=localhost;UID=sa;PASSWORD=;Database=mydatabase;Max Pool Size=400;Connect Timeout=600;";
            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 SqlCommand(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 System.Data.SqlClient;
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()
        {
            SqlConnection objConn = new SqlConnection();
            SqlCommand objCmd = new SqlCommand();
            SqlDataAdapter dtAdapter = default(SqlDataAdapter);
            DataTable dt = new DataTable();
            string strConnString = null;
            string strSQL = null;

            strConnString = "Server=localhost;UID=sa;PASSWORD=;Database=mydatabase;Max Pool Size=400;Connect Timeout=600;";
            objConn.ConnectionString = strConnString;
            objConn.Open();

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

            dtAdapter = new SqlDataAdapter(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();
        }
    }
}