I have a database table where TAGNAMEID, DATETIME, TAGNAMEVALUE are the columns. The values in each columns may look as:
555, 6-14-2007 12:34:00, 23.51
666, 6-14-2007 12:34:00, 190.32
555, 6-15-2007 12:34:00, 21.31
666, 6-15-2007 12:34:00, 187.35
555, 6-16-2007 12:34:00, 32.37
666, 6-16-2007...