les16_oracle9i日期函數(shù)ppt課件

1、Oracle9i 日期函數(shù) 目的經(jīng)過本章學(xué)習(xí)，您將可以運(yùn)用以下日期函數(shù):TZ_OFFSETCURRENT_DATECURRENT_TIMESTAMPLOCALTIMESTAMPDBTIMEZONESESSIONTIMEZONEEXTRACTFROM_TZTO_TIMESTAMPTO_TIMESTAMP_TZTO_YMINTERVAL時區(qū)-08:00上圖顯示了全球24個時區(qū)以及當(dāng)格林威治時間是 12:00時各時區(qū)的時差-05:00+02:00+10:00+07:00Oracle9i 日期支持Oracle9i中, 可以將時區(qū)參與到日期和時間中而且可以將秒進(jìn)展進(jìn)一步的準(zhǔn)確日期中參與了三種新的數(shù)據(jù)類型

2、:TIMESTAMP時間撮TIMESTAMP WITH TIME ZONE (TSTZ) 帶時區(qū)的時間撮TIMESTAMP WITH LOCAL TIME ZONE (TSLTZ) 帶有本地時區(qū)的時間撮Oracle9i 支持夏令時TZ_OFFSETSELECT TZ_OFFSET(US/Eastern) FROM DUAL;SELECT TZ_OFFSET(Canada/Yukon) FROM DUAL; SELECT TZ_OFFSET(Europe/London) FROM DUAL; 顯示時區(qū) US/Eastern的時差 顯示時區(qū) Canada/Yukon的時差 顯示時區(qū) Europe/

3、London的時差 CURRENT_DATECURRENT_DATE 對會話所在的時區(qū)是敏感的ALTER SESSION SET TIME_ZONE = -8:0;SELECT SESSIONTIMEZONE, CURRENT_DATE FROM DUAL;ALTER SESSION SET TIME_ZONE = -5:0;SELECT SESSIONTIMEZONE, CURRENT_DATE FROM DUAL;按照當(dāng)前會話的時區(qū)顯示當(dāng)前會話的時間ALTER SESSION SET NLS_DATE_FORMAT = DD-MON-YYYY HH24:MI:SS;CURRENT_TIME

4、STAMPALTER SESSION SET TIME_ZONE = -8:0;SELECT SESSIONTIMEZONE, CURRENT_TIMESTAMP FROM DUAL;ALTER SESSION SET TIME_ZONE = -5:0;SELECT SESSIONTIMEZONE, CURRENT_TIMESTAMP FROM DUAL;按照當(dāng)前會話的時區(qū)顯示當(dāng)前會話的時間CURRENT_TIMESTAMP 對會話所在的時區(qū)是敏感的前往值是 TIMESTAMP WITH TIME ZONE 數(shù)據(jù)類型LOCALTIMESTAMPALTER SESSION SET TIME_ZO

5、NE = -5:0;SELECT CURRENT_TIMESTAMP, LOCALTIMESTAMP FROM DUAL;ALTER SESSION SET TIME_ZONE = -8:0;SELECT CURRENT_TIMESTAMP, LOCALTIMESTAMP FROM DUAL;按照當(dāng)前會話的時區(qū)顯示當(dāng)前會話的時間LOCALTIMESTAMP對會話所在的時區(qū)是敏感的前往值是 TIMESTAMP 數(shù)據(jù)類型DBTIMEZONE 和 SESSIONTIMEZONE SELECT DBTIMEZONE FROM DUAL;SELECT SESSIONTIMEZONE FROM DUAL;

6、顯示數(shù)據(jù)庫所在的時區(qū)顯示會話所在的時區(qū)EXTRACTSELECT EXTRACT (YEAR FROM SYSDATE) FROM DUAL;SELECT last_name, hire_date, EXTRACT (MONTH FROM HIRE_DATE)FROM employeesWHERE manager_id = 100;從 SYSDATE 中抽出年從HIRE_DATE 中抽出月FROM_TZ 運(yùn)用舉例SELECT FROM_TZ(TIMESTAMP 2000-03-28 08:00:00,3:00)FROM DUAL;SELECT FROM_TZ(TIMESTAMP 2000-03

7、-28 08:00:00, Australia/North)FROM DUAL; SELECT TO_TIMESTAMP_TZ(1999-12-01 11:00:00 -8:00, YYYY-MM-DD HH:MI:SS TZH:TZM)FROM DUAL;TO_TIMESTAMP 和 TO_TIMESTAMP_TZ 運(yùn)用舉例 SELECT TO_TIMESTAMP (2000-12-01 11:00:00, YYYY-MM-DD HH:MI:SS) FROM DUAL;TO_YMINTERVAL 運(yùn)用舉例 SELECT hire_date, hire_date + TO_YMINTERVAL(01-02) AS HIRE_DATE_YMININTERVAL FROM EMPLOYEESWHERE department_id = 20; 總結(jié)TZ_OFFSETFROM_TZTO_TIMESTAMPTO_TIMESTAMP_TZTO_YMINTERVALCURRENT_D