Oracle - 將日/月添加到TIMESTAMP WITH TIME ZONE字段

Question

我需要動態地將某些天（或幾個月）添加到現有TIMESTAMP WITH TIME ZONE字段。

select DATED from MY_TABLE where ID = 1165; 

給出：

DATED 
--------------------------------------------------------------------------- 
20-FEB-16 04.31.54 AM EUROPE/MOSCOW 

當我運行：

UPDATE MY_TABLE SET DATED = DATED + 2 WHERE ID = 1165; 

它給：

DATED 
--------------------------------------------------------------------------- 
22-FEB-16 04.31.54 AM +03:00 

因此，如何適當加2天，不丟失時間戳「 EUROPE/MOSCOW「

如何以與天相同的方式添加2個月？

Answer 1

當你這樣做DATED = DATED + 2，然後是DATED隱式轉換爲DATE值（不具有任何時區信息），然後使用您的當前會話的時區設置轉換回TIMESTAMP WITH TIME ZONE值。

嘗試

UPDATE MY_TABLE SET DATED = DATED + INTERVAL '2' DAY WHERE ID = 1165; 

或

UPDATE MY_TABLE SET DATED = DATED + 2 * INTERVAL '1' DAY WHERE ID = 1165; 

或

UPDATE MY_TABLE SET DATED = DATED + NUMTODSINTERVAL(2, 'day') WHERE ID = 1165; 

爲了加2月份，您可以使用

UPDATE MY_TABLE SET DATED = DATED + INTERVAL '2' MONTH WHERE ID = 1165; 

resp。例如，NUMTOYMINTERVAL(2, 'MONTH')。

Answer 2

使用INTERVAL添加個月的問題是，如果沒有足夠的天所產生的一個月會引發錯誤：

SELECT TIMESTAMP '2016-01-30 00:00:00.000' AT TIME ZONE 'UTC' 
     + INTERVAL '1' MONTH 
FROM DUAL; 

給出：

ORA-01839: date not valid for month specified 

然而，你可以寫一個簡單的（ish）函數來執行算術運算：

Oracle Setup：

CREATE OR REPLACE FUNCTION TS_ADD_MONTHS(
    datetime TIMESTAMP WITH TIME ZONE, 
    months INT 
) RETURN TIMESTAMP WITH TIME ZONE DETERMINISTIC 
AS 
    p_tz CONSTANT VARCHAR2(30) := EXTRACT(TIMEZONE_REGION FROM datetime); 
    p_utc CONSTANT TIMESTAMP := datetime AT TIME ZONE 'UTC'; 
    p_date CONSTANT DATE   := TRUNC(p_utc); 
BEGIN 
    RETURN CAST(ADD_MONTHS(p_date, months) AS TIMESTAMP WITH TIME ZONE) AT TIME ZONE p_tz + (p_utc - p_date); 
END; 
/
SHOW ERRORS; 

查詢：

SELECT TS_ADD_MONTHS(
     TIMESTAMP '2016-01-30 12:12:12.012 EST', 
     1 
     ) AS datetime 
FROM DUAL; 

輸出：

DATETIME 
-------------------------------- 
29-FEB-16 12.12.12.012000000 EST