ASP.Net: Handling Null column values in SqlDataReader using VB.Net

Check the SqlDataReader column using IsDBNull function.

Refer below code.

Using koneksi As New SqlConnection(ambilstringkoneksi)
    Dim perintah As SqlCommand = New SqlCommand("select * from tempimage where idp='123'", koneksi)
    perintah.CommandType = CommandType.Text
    koneksi.Open()
    Dim myreader As SqlDataReader = perintah.ExecuteReader(CommandBehavior.CloseConnection)
    If myreader.Read() Then
        If Not myreader.IsDBNull(myreader("img")) Then
            Dim bytes() As Byte = CType(myreader("img"), Byte())
            Response.Cache.SetCacheability(HttpCacheability.NoCache)
            Response.BinaryWrite(bytes)
            Response.Flush()
            Response.End()
        End If
    Else
        MsgBox("data not found")
    End If
    myreader.Close()
    koneksi.Close()
End Using