Partial Class MasterPage
    Inherits System.Web.UI.MasterPage
 
    Public login As New Class1
 
 
    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim u As String
 
        login.cmd.Connection = login.con
        login.cmd.CommandText = "select * from REG where user = '" + RTrim(TextBox1.Text) + "'"
        login.cmd.ExecuteNonQuery()
 
        login.rdr = login.cmd.ExecuteReader()
 
        If login.rdr.HasRows = True Then
            login.rdr.Read()
            u = login.rdr.Item("pwd")
            If RTrim(TextBox2.Text) = Trim(u) Then
                Response.Redirect("student1.aspx")
            End If
        Else
            MsgBox("Enter correct password", MsgBoxStyle.Critical)
 
        End If
 
        'Try
 
        'Catch ex As Exception
        '    MsgBox(ex.Message)
 
        'End Try
    End Sub
 
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        login.connection()
 
    End Sub
End Class

Imports Microsoft.VisualBasic
Imports System.Data
Imports System.Data.SqlClient
 
 
Public Class Class1
    Public con As SqlConnection
    Public cmd As New SqlCommand
    Public rdr As SqlDataReader
    Public Function connection()
        con = New SqlConnection("Data Source=ANGEL\SQLEXPRESS;Initial Catalog=swas;Integrated Security=True")
        con.Open()
        Return 0
 
    End Function
End Class

cmd.commandtext =  "SELECT count(*) FROM reg WHERE user= '" + RTrim(TextBox1.Text) + "' AND pwd = '" & RTrim(TextBox2.Text) & "'
 
cmd.connection.open
counter = cmd.ExecuteScalar
cmd.connection.close
 
 
 
if counter <= 0 then  ... (user + pw combination unknown)
 

 
Dim conn As SqlConnection
Dim strConn As String = "Data Source=ANX134\SQLEXPRESS;Initial Catalog=Dyslexia_Begin;Integrated Security=True"
 
conn = New SqlConnection(strConn)
conn.Open()
 
SQLcmd = "select * FROM UserDetails where username = '" & txt_username.Text.Trim & "' and password = '" & txt_password.Text & "'"
 
    Public Function CheckExist(ByVal sSQL As String) As Boolean
        sqlcmd = New SqlCommand(sSQL, conn)
        DReader = sqlcmd.ExecuteReader()
        If DReader.Read() Then
            CheckExist = True
        Else
            CheckExist = False
        End If
        DReader.Close()
    End Function
 
'call this function in your code then...