A program that uses all the memory from the sql listview table, how to fill only the relevant data?

I think I have a list that uses all my memory. let me explain what I'm doing

I have a device from which I take messages, I timestamp them, and I add them to sqldatabase

            myConnection.Open();
            SqlCommand cmd = new SqlCommand("INSERT INTO Messages (Time, Message) Values ('" + DateTime.Now + "', '"+sqlMessage+"')", myConnection);
            cmd.ExecuteNonQuery();
            myConnection.Close();
            UpdateTable();

here as i update my list:

            myConnection.Open();
            myCommand.Connection = myConnection;
            adapter.SelectCommand = myCommand;
            myCommand.CommandText = "SELECT * FROM Messages";

            DataSet ds = new DataSet();
            adapter.Fill(ds);


            lvwMessages.DataContext = ds.Tables[0].DefaultView;
            myConnection.Close();

when I leave this for a while, my program usually runs out of memory. I assume that in listview too many posts are loaded from the database. but let me say that I have 15 lines of messages that I need on the screen. how do i load only 15 that i need and then pop those that don't need to be removed from memory and load new ones?