string sql = "select * from CONCURRENCY WHERE CONCURRENCY.DATE_FLAG BETWEEN  cdate('2013-11-1',) AND cdate('2013-11-12')";

这是文本类型转成日期类型的查询

string sql = "select * from CONCURRENCY WHERE CONCURRENCY.DATE_FLAG BETWEEN  #2013-11-1 1:00:02# AND #2013-11-12 11:00:02# order by CONCURRENCY.DATE_FLAG ";

这是长时间类型的格式化，注意这么查询的时候，access存的是时间类型