LOGIN FORM USING LOOP

Private Sub LOGIN_BUTTON_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles LOGIN_BUTTON.Click

        Try

            con = New SqlConnection(Module1.mod1)

            con.Open()

            sql = "select * from M_LOGIN WHERE LOGIN_ID = '" & Me.UsernameTextBox.Text & "' and pass1 = '" & Me.PasswordTextBox.Text & "' and pass2 = '" & Me.PasswordTextBox.Text & "'"

            cmd = New SqlCommand(sql, con)

            dr = cmd.ExecuteReader

            If dr.Read() Then

                Form1.Show()

                Me.Hide()

            Else : MsgBox("Invalid UserName or Password", 16, "LOGIN ERROR")

            End If

        Catch es As Exception

            MsgBox(es.Message)

        End Try

        con.Close()

        Me.UsernameTextBox.Clear()

        Me.PasswordTextBox.Clear()

        Me.UsernameTextBox.Select()

    End Sub

USING WHILE LOOP / IF ELSE

Imports System.Data.OleDb

Imports System.Data

Public Class login

    Dim con As OleDbConnection, cmd As OleDbCommand

    Dim str1 As String

    Dim str2 As String

    Private Sub Login_Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        con = New OleDbConnection("Provider=Microsoft.JET.OLEDB.4.0;Data Source=" & Application.StartupPath & "\database1.mdb;Persist security Info=False")

        str1 = "select [StudentNumber],[StudentPassword] from [Members] WHERE [StudentNumber] like '" & Trim(TextBox1.Text) & "' and [StudentPassword] like '" & Trim(TextBox2.Text) & "';"

        str2 = "select [AUserName],[APassword] from [Members2] WHERE [AUserName] like '" & Trim(TextBox1.Text) & "' and [APassword] like '" & Trim(TextBox2.Text) & "';"

        cmd = New OleDbCommand(str1, con)

        cmd2 = New OleDbCommand(str2, con)

        Dim dr As OleDbDataReader

        Dim dr2 As OleDbDataReader

        dr = cmd.ExecuteReader

        dr2 = cmd2.ExecuteReader

        If dr.HasRows = False Then

            If dr2.HasRows = False Then

                MsgBox("Please enter a correct username or password")

            End If

        Else

            While (dr.Read())

                If (TextBox1.Text = dr(0).ToString()) And (TextBox2.Text = dr(1).ToString()) Then

                    student_form.Show()

                    Me.Hide()

                    TextBox1.Text = ""

                    TextBox2.Text = ""

                End If

            End While

            dr.Close()

        End If

        While (dr2.Read())

            If (TextBox1.Text = dr2(0).ToString()) And (TextBox2.Text = dr2(1).ToString()) Then

                admin_form.Show()

                Me.Hide()

                TextBox1.Text = ""

                TextBox2.Text = ""

            End If

        End While

        dr.Close()

        cmd = Nothing

        cmd2 = Nothing

        con.Close()

    End Sub

    Private Sub Cancel_Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click

        End

        Me.Dispose()

    End Sub

End Class