Login Form in VB.NET with SQL

Prerequisites

• Visual Studio: Ensure you have Visual Studio installed with support for VB.NET and SQL Server.
• SQL Server: SQL Server should be installed and running. You can use SQL Server Express for a lightweight option.

Step 1: Set Up the SQL Database

1. Create a New Database

   • Open SQL Server Management Studio (SSMS).
   • Connect to your SQL Server instance.
   • Right-click on Databases and select New Database.
   • Name the database (e.g., UserDatabase) and click OK.

2. Create a Table for User Credentials

   • Right-click on the newly created database and select New Query.

   • Enter the following SQL script to create a table for storing user credentials:

      

     CREATE TABLE Users ( UserID INT PRIMARY KEY IDENTITY(1,1), Username NVARCHAR(50) NOT NULL UNIQUE, PasswordHash NVARCHAR(256) NOT NULL );

   • Run the script by clicking the Execute button

1. Add SQL Database Connection

   • In Solution Explorer, right-click on your project and select Add -> New Item -> Class. Name it DatabaseHelper.vb.

   • Add the following code to handle database connections and queries:

     Imports System.Data.SqlClient Public Class DatabaseHelper Public Function ValidateUser(username As String, password As String) As Boolean Dim query As String = "SELECT COUNT(*) FROM Users WHERE Username = @Username AND PasswordHash = HASHBYTES('SHA2_256', @Password)" Using connection As New SqlConnection(ConnectionString) Using command As New SqlCommand(query, connection) command.Parameters.AddWithValue("@Username", username) command.Parameters.AddWithValue("@Password", password) connection.Open() Dim result As Integer = Convert.ToInt32(command.ExecuteScalar()) Return result > 0 End Using End Using End Function End Class

   • Replace YOUR_SERVER_NAME with your SQL Server instance name.

2. Write the Code for the Login Button

• Double-click on the Login Button (btnLogin) to open the code editor.

• Add the following code to handle user login:

   

  Public Class LoginFrom1 Private Sub btnLogin_Click(sender As Object, e As EventArgs) Handles btnLogin.Click Dim username As String = txtUsername.Text Dim password As String = txtPassword.Text If dbHelper.ValidateUser(username, password) Then MessageBox.Show("Login successful!", "Success", MessageBoxButtons.OK, MessageBoxIcon.Information) Else MessageBox.Show("Invalid username or password. Please try again.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error) End If End Sub
• Private Function ValidateUser(username As String, password As String) As Boolean
• Dim ConnectionString As String = "Server=YOUR_SERVER_NAME;Database=UserDatabase;Trusted_Connection=True;"
• Dim query As String = "SELECT COUNT(*) FROM Users WHERE Username = @Username AND PasswordHash = HASHBYTES('SHA2_256', @Password)" Using connection As New SqlConnection(ConnectionString) Using command As New SqlCommand(query, connection) command.Parameters.AddWithValue("@Username", username) command.Parameters.AddWithValue("@Password", password) connection.Open() Dim result As Integer = Convert.ToInt32(command.ExecuteScalar()) Return result > 0 End Using End Using End Function

Step 3: Test Your Application

1. Run Your Application
   • Press F5 to run the application.
   • Enter the username and password (e.g., admin and password123) and click the Login button.
   • You should see a success message if the credentials are correct, or an error message if they are not.