//parameterized update query
string updateCommandString = "UPDATE RoomsTable SET [Date Checked]=@checkedDate WHERE ID = @id";
using (OleDbConnection conn = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=c:userssprestondocumentsvisual studio 2012ProjectsroomChecksProgramroomChecksProgramroomsBase.accdb"))
{

    using (OleDbCommand updateCommand = new OleDbCommand())
    {
        OleDbTransaction transaction = null;
        updateCommand.Connection = conn;
        updateCommand.Transaction = transaction;
        updateCommand.CommandText = updateCommandString;
        updateCommand.CommandType = CommandType.Text;
        updateCommand.Parameters.AddWithValue("@checkedDate", this.dateTimePicker1.Value.ToShortDateString());
        updateCommand.Parameters.AddWithValue("@id", row.roomID);
        try
        {
            conn.Open();
            transaction = conn.BeginTransaction();
            updateCommand.Transaction = transaction;
            updateCommand.ExecuteNonQuery();
            transaction.Commit();
            conn.Close();
            conn.Dispose();
        }
        catch(OleDbException ex)
        {
            MessageBox.Show(ex.Message.ToString());
        }
    }
}

class SomethingDA {
   static DataTable GetMyStuff(your params) {
     // establish connection, get your results
   }
}