在工作中需要计算两个时间的差值，结束时间 - 开始时间，又不想在js里写function，也不想在Java里去计算，干脆就在Oracle数据库做了一个函数来计算两个时间的差值。格式为XX天XX时XX分XX秒；
上代码：
CREATE OR REPLACE FUNCTION F_GET_DIFF_TIME(START_TIME IN DATE,
END_TIME IN DATE)
RETURN VARCHAR2 IS
DIFF_TIME VARCHAR2(50);
BEGIN
SELECT TDAY || '天' || THOUR || '时' || TMINUTE || '分' || ROUND((TT - TMINUTE) * 60) || '秒' INTO DIFF_TIME
FROM (SELECT TDAY,
THOUR,
TRUNC((TT - THOUR) * 60) TMINUTE,
(TT - THOUR) * 60 TT
FROM (SELECT TDAY,
TRUNC((TT - TDAY) * 24) THOUR,
(TT - TDAY) * 24 TT
FROM (SELECT TO_NUMBER(END_TIME - START_TIME) AS TT,
TRUNC(TO_NUMBER(END_TIME - START_TIME)) AS TDAY
FROM (SELECT START_TIME, END_TIME FROM dual))));
RETURN DIFF_TIME;
END;
输出的格式为下图：
