日付から曜日を取得する
2012-02-09
2012-02-01
2011-12-30
2011-12-19
2011-12-14
2011-11-22
2011-11-21
2011-11-09
2011-10-26
2011-10-21
2011-10-06
2011-10-03
2011-09-10
SELECT (ARRAY['日','月','火','水','木','金','土'])[EXTRACT(DOW FROM CAST('2009-09-28 19:30' AS DATE)) + 1];