数据库自定义函数（date和utc时间相互转换）

  /**  * 根据日期获得utc值  */create or replace function fun_date2utc(p_date in date) return number is  utc number;begin   utc := 86400 * (p_date - to_date('1970/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS')) - 8*3600;   return utc;end fun_date2utc;  /*-- name: utc2date  -- return: date  -- param: p_utc [in] NUMBER: UTC(s)根据utc转成日期  */create or replace function fun_utc2date(p_utc in NUMBER) return DATE is  p_date DATE;begin   p_date := (p_utc + 8*3600) / 86400 + to_date('1970/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS');   return p_date;end fun_utc2date;