Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    Dim strConn As String = "Data Source=VICKY03-MSFT;Initial Catalog=Xueyun;Integrated Security=True"

    'Named a alias Larcolais for price column
    Dim strsql As String = "SELECT price AS Larcolais FROM parent WHERE startDate = '" & TextBox1.Text & "'"
    Dim conn As New SqlConnection(strConn)
    conn.Open()
    Dim cmd As New SqlCommand(strsql, conn)
    Dim reader As SqlDataReader = cmd.ExecuteReader
    'begin reader
    reader.Read()
    'if textbox2's text was greater than the current value of Larcolais column, the prompt window was occurred
    If TextBox2.Text > reader("Larcolais") Then
      MsgBox("alert")
    End If

  End Sub

Using connection = New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0; Data Source=H:\Computing\Year 13\Computing Project Course-work\Database41.accdb")
Using command = New OleDbCommand("SELECT SUM(Distance) As Total FROM [Table3];", Conn)
    Dim total = Convert.ToInt32(command.ExecuteScalar)
    TextBox7.Text = total.ToString
End Using
End Using