(Les16 Managing Data in Different Time Zones)[20171230]

Posted 2020-10-19 also-brook

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学习目标：

-current_date 当前时间 TZ_OFFSET

-current_timestamp 含小数秒当前时间 FROM_TZ

-localtimestamp 含小数秒本地时间 TO_TIMESTAMP

-dbtimezone 数据库时区 TO_TIMSTAMP_TZ

-sessiontimezone 回话时间时区 TO_YMINTERVAL

-extract 提取 TO_DSINTERVAL

TIME_ZONE会话参数

可以设定为以下值

-一个绝对偏移值

-数据库时区

-系统本地时区

-一个区域名称

ALTER SESSION SET TIME_ZONE = ‘-06:00‘;

ALTER SESSION SET TIME_ZONE = dbtimezone;

ALTER SESSION SET TIME_ZONE = local;

ALTER SESSION SET TIME_ZONE = ‘America/New_York‘;

SYS@cqoraxt0>ALTER SESSION SET TIME_ZONE = dbtimezone;
Session altered.
SYS@cqoraxt0>select systimestamp from dual;
SYSTIMESTAMP
---------------------------------------------------------------------------
29-DEC-17 10.50.13.546588 PM +08:00 ->当前数据库所在时区的时间
SYS@cqoraxt0>select localtimestamp from dual;
LOCALTIMESTAMP
---------------------------------------------------------------------------
29-DEC-17 02.50.38.464141 PM
SYS@cqoraxt0>ALTER SESSION SET TIME_ZONE = dbtimezone;
Session altered.
SYS@cqoraxt0>select localtimestamp from dual;
LOCALTIMESTAMP
---------------------------------------------------------------------------
29-DEC-17 02.50.49.337510 PM
SYS@cqoraxt0>ALTER SESSION SET TIME_ZONE = ‘-06:00‘;
Session altered.
SYS@cqoraxt0>select localtimestamp from dual;
LOCALTIMESTAMP
---------------------------------------------------------------------------
29-DEC-17 08.51.00.307601 AM->绝对偏移量的时区
SYS@cqoraxt0>ALTER SESSION SET TIME_ZONE = local;
Session altered.
SYS@cqoraxt0>select localtimestamp from dual;
LOCALTIMESTAMP
---------------------------------------------------------------------------
29-DEC-17 10.51.11.989536 PM->系统本地时间时区
SYS@cqoraxt0>ALTER SESSION SET TIME_ZONE = ‘America/New_York‘;
Session altered.
SYS@cqoraxt0>select localtimestamp from dual;
LOCALTIMESTAMP
---------------------------------------------------------------------------
29-DEC-17 09.51.21.599491 AM ->指定时间区域名称

　　CURRENT_DATE,CURRENT_TIMESTAMP,LOCALTIMESTAMP

-CURRENT_DATE 当前时间同sysdate表达一样

-CURRENT_TIMESTAMP 含时区

　　　 -LOCALTIMESTAMP 不含时区　　　

col CURRENT_DATE format a30
            col SESSIONTIMEZONE format a20
            col CURRENT_TIMESTAMP format a40
            col LOCALTIMESTAMP format a40
            col sysdate format a30
            set linesize 300
            alter session set nls_date_format=‘YYYY-MM-DD HH24:MI:SS‘; 
            --调整时间输出的格式
            select sessiontimezone,current_date,current_timestamp,localtimestamp,sysdate from dual;
        
SESSIONTIMEZONE      CURRENT_DATE                   CURRENT_TIMESTAMP                        LOCALTIMESTAMP                           SYSDATE
-------------------- ------------------------------ ---------------------------------------- ---------------------------------------- ------------------------------
+08:00               2017-12-29 23:13:08            29-DEC-17 11.13.08.826336 PM +08:00      29-DEC-17 11.13.08.826336 PM             2017-12-29 23:13:08

DBTIMEZONE,SESSIONTIMEZONE

-DBTIMEZONE 数据库时区，也就是0时区

-SESSIONTIMEZONE 会话的当前时区

  
            col SESSIONTIMEZONE format a20
            col sysdate format a30
            set linesize 300
            alter session set nls_date_format=‘YYYY-MM-DD HH24:MI:SS‘; 
            --调整时间输出的格式
            select dbtimezone,sessiontimezone,sysdate from dual;
DBTIME SESSIONTIMEZONE      SYSDATE
------ -------------------- ------------------------------
+00:00 +08:00               2017-12-29 23:16:04

TIMESTAMP 时间类型

-TIMESTAMP [(fractional_seconds_precision)] 包含：年，月，天，小时，分钟，秒，时区小时，时区分钟

-TIMESTAMP [(fractional_seconds_precision)] WITH TIME ZONE

-TIMESTAMP [(fractional_seconds_precision)] WITH LOCAL TIME ZONE

TIMESTAMP时间类型各个值的范围

DATE,TIMESTAMP的不同点

-TIMESTAMP相比DATE多小数秒，时区小时和时区分钟。

create table time_t01(
id number,
t_date date default sysdate,
t_timestamp timestamp default current_timestamp
)
/
insert into time_t01 values(1,default,default);
/
col t_date format a30
col t_timestamp format a40
set linesize 300
alter session set nls_date_format=‘YYYY-MM-DD HH24:MI:SS‘;
--调整会话输出时时间格式
select * from time_t01;
 
        ID T_DATE                         T_TIMESTAMP
---------- ------------------------------ ----------------------------------------
         1 2017-12-29 23:51:55            29-DEC-17 11.51.55.085972 PM

--添加一个栏位
alter table time_t01 add (t_timestamp_zone timestamp with time zone);
 
insert into time_t01 values(2,default,default,timestamp‘2017-12-29 23:57:00 +8:00‘);
commit;
insert into time_t01 values(3,default,default,timestamp‘2017-12-29 23:57:00 America/New_York‘);
commit;
insert into time_t01 values(4,default,default,timestamp‘2017-12-29 23:57:00 -8:00‘);
commit;
col t_timestamp_zone format a50
select * from time_t01;
        ID T_DATE                         T_TIMESTAMP                              T_TIMESTAMP_ZONE
---------- ------------------------------ ---------------------------------------- --------------------------------------------------
         1 2017-12-29 23:51:55            29-DEC-17 11.51.55.085972 PM
         2 2017-12-29 23:57:39            29-DEC-17 11.57.39.696414 PM             29-DEC-17 11.57.00.000000 PM +08:00
         3 2017-12-30 00:02:51            30-DEC-17 12.02.51.376596 AM             29-DEC-17 11.57.00.000000 PM AMERICA/NEW_YORK
         4 2017-12-30 00:02:51            30-DEC-17 12.02.51.385169 AM             29-DEC-17 11.57.00.000000 PM -08:00
 
  --添加一个栏位
 alter table time_t01 add (t_timestamp_local_zone timestamp with local time zone);
 insert into time_t01 values(5,default,default,current_timestamp,current_timestamp);
 col t_timestamp_local_zone format a50
 select * from time_t01 order by id;
                ID T_DATE                         T_TIMESTAMP                              T_TIMESTAMP_ZONE                                   T_TIMESTAMP_LOCAL_ZONE
---------- ------------------------------ ---------------------------------------- -------------------------------------------------- --------------------------------------------------
         1 2017-12-29 23:51:55            29-DEC-17 11.51.55.085972 PM
         2 2017-12-29 23:57:39            29-DEC-17 11.57.39.696414 PM             29-DEC-17 11.57.00.000000 PM +08:00
         3 2017-12-30 00:02:51            30-DEC-17 12.02.51.376596 AM             29-DEC-17 11.57.00.000000 PM AMERICA/NEW_YORK
         4 2017-12-30 00:02:51            30-DEC-17 12.02.51.385169 AM             29-DEC-17 11.57.00.000000 PM -08:00
         5 2017-12-30 00:07:05            30-DEC-17 12.07.05.688410 AM             30-DEC-17 12.07.05.688410 AM +08:00                30-DEC-17 12.07.05.688410 AM
        
 改变会话当前时区，timestamp with local time zone 时间也会跟着变动
 SYS@cqoraxt0>alter session set time_zone=‘-09:00‘;
 Session altered.
 SYS@cqoraxt0> select * from time_t01 order by id;
 
        ID T_DATE                         T_TIMESTAMP                              T_TIMESTAMP_ZONE                                   T_TIMESTAMP_LOCAL_ZONE
---------- ------------------------------ ---------------------------------------- -------------------------------------------------- --------------------------------------------------
         1 2017-12-29 23:51:55            29-DEC-17 11.51.55.085972 PM
         2 2017-12-29 23:57:39            29-DEC-17 11.57.39.696414 PM             29-DEC-17 11.57.00.000000 PM +08:00
         3 2017-12-30 00:02:51            30-DEC-17 12.02.51.376596 AM             29-DEC-17 11.57.00.000000 PM AMERICA/NEW_YORK
         4 2017-12-30 00:02:51            30-DEC-17 12.02.51.385169 AM             29-DEC-17 11.57.00.000000 PM -08:00
         5 2017-12-30 00:07:05            30-DEC-17 12.07.05.688410 AM             30-DEC-17 12.07.05.688410 AM +08:00                29-DEC-17 07.07.05.688410 AM

INTERVAL时间类型

-INTERVAL用于存储两个时间差

-年-月 Year-month INTERVAL YEAR TO MONTH

-天-时间 Day-time INTERVAL DAY TO SECOND

INTERVAL YEAR (year_precision) TO MONTH

INTERVAL DAY (day_precision) TO SECOND (fractional_seconds_precision)

create table time_t02(
id number,
t_interval_y interval year to month,
t_interval_d interval day to second
)
/
insert into time_t02 values(1,‘03-5‘ ,‘05 12:00:00‘)
/
insert into time_t02 values(2,interval ‘04‘ year,interval ‘06 13:00:00‘ day to second )
/
insert into time_t02 values(3,interval ‘12‘ month,interval ‘07 14:00:00‘ day to second )
/
 
 
alter session set nls_date_format=‘YYYY-MM-DD HH24:MI:SS‘;
col t_interval_y format a30
col t_interval_d format a30
select * from time_t02;
 
        ID T_INTERVAL_Y                   T_INTERVAL_D
---------- ------------------------------ ------------------------------
         1 +03-05                         +05 12:00:00.000000
         2 +04-00                         +06 13:00:00.000000
         3 +01-00                         +06 13:00:00.000000

EXTRACT 提取时间

-可提取时间类型

EXTRACT ([YEAR] [MONTH][DAY] [HOUR] [MINUTE][SECOND] [TIMEZONE_HOUR] [TIMEZONE_MINUTE] [TIMEZONE_REGION] [TIMEZONE_ABBR]

-年、月、天、小时、分钟、秒、时区小时、时区分钟、时区区域、时区缩写

set linezie 600
col zone_region format a20
col zone_abbr format a20
select
    extract(year from t_timestamp_zone) year,
    extract(month from t_timestamp_zone) month,
    extract(day from t_timestamp_zone) day,
    extract(hour from t_timestamp_zone) hour,
    extract(minute from t_timestamp_zone) minute,
    extract(second from t_timestamp_zone) second,
    extract(timezone_hour from t_timestamp_zone) zone_hour,
    extract(timezone_minute from t_timestamp_zone) zone_minute,
    extract(timezone_region from t_timestamp_zone) zone_region,
    extract(timezone_abbr from t_timestamp_zone) zone_abbr
    from time_t01
where id=3
/
            
                  YEAR      MONTH        DAY       HOUR     MINUTE     SECOND  ZONE_HOUR ZONE_MINUTE
---------- ---------- ---------- ---------- ---------- ---------- ---------- -----------
ZONE_REGION          ZONE_ABBR
-------------------- --------------------
      2017         12         30          4         57          0         -5           0
America/New_York     EST

时区转换函数

-TZ_OFFSET 时间区域转为为数值

TZ_OFFSET ( [‘time_zone_name‘] ‘[+ | -] hh:mm‘ ] [ SESSIONTIMEZONE] [DBTIMEZONE]

SYS@cqoraxt0>select tz_offset(‘America/New_York‘) from dual;
TZ_OFFS
-------
-05:00

V$TIMEZONE_NAMES所有时区区域名称视图

-FROM_TZ 将TIMESTAMP转换为TIMESTAMP WITH TIME ZONE

FROM_TZ(TIMESTAMP timestamp_value, time_zone_value)

SYS@cqoraxt0>select from_tz(timestamp ‘2017-12-30 23:50:00‘,‘+8:00‘) from dual;
FROM_TZ(TIMESTAMP‘2017-12-3023:50:00‘,‘+8:00‘)
---------------------------------------------------------------------------
30-DEC-17 11.50.00.000000000 PM +08:00

-TO_TIMESTAMP 将字符串转为TIMESTAMP时间类型

TO_TIMESTAMP (char,[fmt],[‘nlsparam‘])

SYS@cqoraxt0>select to_timestamp(‘2017-12-30 23:53:00‘,‘YYYY-MM-DD HH24:MI:SS‘) from dual;
TO_TIMESTAMP(‘2017-12-3023:53:00‘,‘YYYY-MM-DDHH24:MI:SS‘)
---------------------------------------------------------------------------
30-DEC-17 11.53.00.000000000 PM

-TO_TIMESTAMP_TZ 将字符串转为TIMESTAMP WITH TIME ZONE

TO_TIMESTAMP_TZ (char,[fmt],[‘nlsparam‘])

SYS@cqoraxt0>select to_timestamp_tz(‘2017-12-30 23:55:00 +8:00‘,‘YYYY-MM-DD HH24:MI:SS TZH:TZM‘) from dual;
           TO_TIMESTAMP_TZ(‘2017-12-3023:55:00+8:00‘,‘YYYY-MM-DDHH24:MI:SSTZH:TZM‘)
---------------------------------------------------------------------------
30-DEC-17 11.55.00.000000000 PM +08:00

-TO_YMINTERVAL 将字符串转为时间间隔类型INTERVAL YEAR TO MONTH

TO_YMINTERVAL(char)

 SYS@cqoraxt0>select sysdate+to_yminterval(‘01-01‘) from  dual;
SYSDATE+TO_YMINTERV
-------------------
2019-01-31 00:03:14

-TO_DSINTERVAL 将字符串转为时间间隔类型INTERVAL DAY TO SECOND

TO_DSINTERVAL(char)

 SYS@cqoraxt0>select sysdate+to_dsinterval(‘05 1:00:00‘) from dual;
            SYSDATE+TO_DSINTERV
            -------------------
            2018-01-05 01:06:57

学习总结：

1.5个时间current_date、current_timestamp、localtimestamp、dbtimezone、sessionzone

2.时区值的更改及对应可选值数据库时区、系统时区、偏移量值、时区区域名称

3.时间类型:DATE ,TIMESTAMP,TIMESTAMP WITH TIME ZONE ,TIMESTAMP WITH LOCAL TIME ZONE,INTERVAL YEAR TO MONTH,INTERVAL DAY TO SECOND

4.时间类型中的各个值的提取函数EXTRACT

5.时间类型的转换函数TO_DATE,TZ_OFFSET,FROM_TZ,TO_TIMESTAMP,TO_TIMSTAMP_TZ,TO_YMINTERVAL,TO_DSINTERVAL

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