oracle計算兩個時間的差值（XX天XX時XX分XX秒）

在工做中須要計算兩個時間的差值，結束時間 - 開始時間，又不想在js裏寫function，也不想在java裏去計算，乾脆就在數據庫作了一個函數來計算兩個時間的差值。格式爲XX天XX時XX分XX秒；

上代碼：

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 || '時' || 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;

輸出的格式爲上圖；