c# window login form application

abra man

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

9 Replies

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Vincent Maverick Durano8y ago
Accepted 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/
+1
abra man8y ago
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
+1
abra man8y ago
Yes is VB.net code
+1
Rafnas T P8y ago
Hi, Are you using vb.net? You have posted VB.net code.
+1
Vincent Maverick Durano8y ago
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)
+1
abra man8y ago
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
+1
rajendra singh8y ago
Could you please post what error you were getting while connecting to database, so we can give suggest you in better way.
+1
Rafnas T P8y ago
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
+1
Ranjit Powar8y ago
Post your connection string
+1