ช่วยดูโค้ดเรื่องเชคยูสเซอร์เนมซำ้ให้หน่อยนะครับมันซ้ำแล้วยังบันทึกได้อยู่เลย

   Protected Sub btnsave_Click(sender As Object, e As EventArgs) Handles btnsave.Click
        Dim year As Integer = Convert.ToInt32(DropDownList4.SelectedValue)
        Dim day As String = Convert.ToString(year) + "-" + DropDownList3.SelectedValue + "-" + DropDownList2.SelectedValue
        If IsDate(day) = False Then
            Dim script3 As String = "alert('กรุณาระบุวันเกิดอีกครั้ง!');"
            ScriptManager.RegisterStartupScript(Me, Me.GetType(), "jsCall", script3, True)
            Exit Sub
        End If
        Dim intCount As Integer
        Dim Conn As New SqlConnection(strCon)
        Conn.Open()
        Dim sql As String = "SELECT COUNT(*) FROM REGISTER WHERE USERNAME = '%" & txtusername.Text & "%'"
        Dim com As New SqlCommand
        With com
            .Connection = Conn
            .CommandText = sql
            .CommandType = CommandType.Text
        End With
        intCount = com.ExecuteScalar()
        If intCount > 0 Then
            Dim script3 As String = "alert('ชื่อผู้ใช้มีอยู่แล้ว!');"
            ScriptManager.RegisterStartupScript(Me, Me.GetType(), "jsCall", script3, True)
            Exit Sub
        Else
            Dim sqlb As String = "INSERT INTO [REGISTER]([USERNAME],[PASS],[NAME],[SURNAME],[DATE_OF_BIRTH],[GENDER],[STATUS_ID]) VALUES ( '" + txtusername.Text + "', '" + txtpass.Text + "','" + txtname.Text + "','" + txtsurname.Text + "','" & day & "','" + DropDownList1.SelectedValue + "','2')"
            '--------------------------------------------------------------

            Dim cmd1 = New SqlCommand
            With cmd1
                .Connection = Conn
                .CommandType = CommandType.Text
                .CommandText = sqlb
            End With
            cmd1.ExecuteNonQuery()
            Conn.Close()
            Response.Redirect("index.aspx")

        End If
    End Sub