c# window login form application

Question

I want to create c# window login form application and I want that login form to connect to my SQL database and open the second form. I tried most tutorials but is failing to connect to my database. Please help

Vincent Maverick Durano · Answer

@abra man. As as stated, you should put the code in your Button's click event like this: Private Sub Validate( ByVal userName As String , ByVal passWord As String ) Dim sqlStatement As String = "SELECT * FROM LoginTable WHERE user_name = @UserName and password =@Password" Using connection As SqlConnection = New SqlConnection( "Data Source=ABRAM-PC\SQLEXPRESS;Initial Catalog=Login;Integrated Security=True" ) Using cmd As SqlCommand = New SqlCommand( String .Format(sqlStatement, inclause), connection) cmd.Parameters.AddWithValue( "@UserName" , userName) cmd.Parameters.AddWithValue( "@Password" , passWord) Dim dt As DataTable = New DataTable() Dim ad As SqlDataAdapter = New SqlDataAdapter(cmd) ad.Fill(dt) If dt.Rows.Count > 0 Then MessageBox.Show( "Login succeed" , "Success" , MessageBoxButtons.OK, MessageBoxIcon.Information) Else MessageBox.Show( "Invalid user name and password" , "Access denied" , MessageBoxButtons.OK, MessageBoxIcon.[ Error ]) End If End Using End Using End Sub Private Sub Button1_Click(sender As Object , e As EventArgs) Handles Button1.Click Validate(txtUserName.Text,txtPass.Text) End Sub If you are new to VB.NET Development, I would really suggest you to start learning the basic concepts and how stuff works so you would be able to undertand the code and debug your own code in the future. Here's a link that may serve as a reference: https://www.tutorialspoint.com/vb.net/

abra man · Answer

Thanks Vincent but can you give me step by step, because this is the code on my login Now button . where should the code go? ---------------------------- Public Class Form1 Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click End Sub End Class

abra man · Answer

Yes is VB.net code

Rafnas T P · Answer

Hi, Are you using vb.net? You have posted VB.net code.

Vincent Maverick Durano · Answer

Your code should go within Button's Click event. Just a reminder, you should not append the value of TextBox directly to you SQL string as it can leads you to SQL Injection attack. You should use parameterize query instead. For example: Private Sub Validate( ByVal userName As String , ByVal passWord As String ) Dim sqlStatement As String = "SELECT * FROM LoginTable WHERE user_name = @UserName and password =@Password" Using connection As SqlConnection = New SqlConnection( "YOUR CONNECTION STRING HERE" ) Using cmd As SqlCommand = New SqlCommand( String .Format(sqlStatement, inclause), connection) cmd.Parameters.AddWithValue( "@UserName" , userName) cmd.Parameters.AddWithValue( "@Password" , passWord) Dim dt As DataTable = New DataTable() Dim ad As SqlDataAdapter = New SqlDataAdapter(cmd) ad.Fill(dt) If dt.Rows.Count > 0 Then MessageBox.Show( "Login succeed" , "Success" , MessageBoxButtons.OK, MessageBoxIcon.Information) Else MessageBox.Show( "Invalid user name and password" , "Access denied" , MessageBoxButtons.OK, MessageBoxIcon.[ Error ]) End If End Using End Using End Sub You can then call the method above like this at your Button's Click event: Validate(txtUserName.Text,txtPass.Text)

abra man · Answer

this is the code but I dont know where should the code go on the login button or on the form? ---------------------------------------------------------------------------------------------- Public Class frmLogin Dim con As New SqlClient.SqlConnection Dim da As New SqlClient.SqlDataAdapter Dim ds As New DataSet Dim sqlquery As String Private Sub frmLogin_Load(sender As Object, e As EventArgs) Handles MyBase.Load con.ConnectionString = "Data Source=ABRAM-PC\SQLEXPRESS;Initial Catalog=Login;Integrated Security=True" End Sub Private Sub btnLogin_Click(sender As Object, e As EventArgs) Handles btnLogin.Click Try 'checking if the username and password field is null If Len(Trim(txtUserName.Text)) = 0 Then MessageBox.Show("Enter the user name", "Input Error !", MessageBoxButtons.OK, MessageBoxIcon.Error) Exit Sub txtUserName.Focus() End If If Len(Trim(txtPass.Text)) = 0 Then MessageBox.Show("Enter the password", "Input Error !", MessageBoxButtons.OK, MessageBoxIcon.Error) Exit Sub txtPass.Focus() End If 'executing SQL Query for retrieving the username and password from the database table con.Open() sqlquery = "SELECT * FROM LoginTable WHERE user_name='" & txtUserName.Text & "' and password='" & txtPass.Text & "' " da = New SqlClient.SqlDataAdapter(sqlquery, con) da.Fill(ds, "LoginTable") If ds.Tables("LoginTable").Rows.Count 0 Then MessageBox.Show("Login succeed", "Success", MessageBoxButtons.OK, MessageBoxIcon.Information) Else MessageBox.Show("Invalid user name and password", "Access denied", MessageBoxButtons.OK, MessageBoxIcon.Error) End If con.Close() clear() 'calling clear method here Catch ex As Exception MessageBox.Show(ex.Message, "Exception generated", MessageBoxButtons.OK, MessageBoxIcon.Error) End Try End Sub ' declaring a method for clearing the controls Public Sub clear() txtPass.Clear() txtUserName.Clear() End Sub ' code for show password Private Sub chkshowpass_CheckedChanged(sender As Object, e As EventArgs) Handles chkshowpass.CheckedChanged If chkshowpass.Checked = True Then txtPass.UseSystemPasswordChar = False Else txtPass.UseSystemPasswordChar = True End If End Sub End Class

rajendra singh · Answer

Could you please post what error you were getting while connecting to database, so we can give suggest you in better way.

Rafnas T P · Answer

hi, try below video tutorial https://www.youtube.com/watch?v=tcmmCcMs8yU if you have any problem in any line of code, please post that Thank you

Ranjit Powar · Answer

Post your connection string

c# window login form application

Answers (9)