45.Oracle数据库SQL开发之 日期和时间的存储与处理——使用时间戳
2015-11-09 22:06
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45.Oracle数据库SQL开发之 日期和时间的存储与处理——使用时间戳
欢迎转载，转载请标明出处： http://blog.csdn.net/notbaron/article/details/49745689
9i数据库引入了一种新特性，可以存储时间戳。时间戳可以存储世纪、四位年、月、日、时、分、秒。与DATE类型比，时间戳有以下优点：
n 时间戳可以存储秒的小数位
n 时间戳可以存储时区
CREATE TABLE purchases_with_timestamp (
product_id INTEGER REFERENCES products(product_id),
customer_id INTEGER REFERENCES customers(customer_id),
made_on TIMESTAMP(4)
);
INSERT INTO purchases_with_timestamp (
product_id, customer_id, made_on
) VALUES (
1,1, TIMESTAMP '2005-05-13 07:15:31.1234'
);
查询如下：
store@PDB1> select * frompurchases_with_timestamp;
PRODUCT_ID CUSTOMER_ID MADE_ON
---------- --------------------------------------------------------------------------------------
1 1 13-MAY-05 07.15.31.1234 AM
CREATE TABLE purchases_timestamp_with_tz (
product_id INTEGER REFERENCES products(product_id),
customer_id INTEGER REFERENCES customers(customer_id),
made_on TIMESTAMP(4) WITH TIME ZONE
);
INSERT INTO purchases_timestamp_with_tz (
product_id, customer_id, made_on
) VALUES (
1,1, TIMESTAMP '2005-05-13 07:15:31.1234 -07:00'
);
查看如下内容：
store@PDB1> select * frompurchases_timestamp_with_tz;
PRODUCT_ID CUSTOMER_ID MADE_ON
---------- ----------- ---------------------------------------------------------------------------
1 1 13-MAY-05 07.15.31.1234 AM -07:00
1 2 13-MAY-05 07.15.31.1234 AM PST
CREATE TABLE purchases_with_local_tz (
product_id INTEGER REFERENCES products(product_id),
customer_id INTEGER REFERENCES customers(customer_id),
made_on TIMESTAMP(4) WITH LOCAL TIME ZONE
);
INSERT INTO purchases_with_local_tz (
product_id, customer_id, made_on
) VALUES (
1,1, TIMESTAMP '2005-05-13 07:15:30 EST'
);
INSERT INTO purchases_with_local_tz (
product_id, customer_id, made_on
) VALUES (
2, 2,TIMESTAMP '2005-05-14 07:15:30 PST'
);
查看如下：
store@PDB1> select * from purchases_with_local_tz;
PRODUCT_ID CUSTOMER_ID MADE_ON
---------- --------------------------------------------------------------------------------------
2 2 14-MAY-05 09.15.30.0000 AM
1 1 13-MAY-05 07.15.30.0000 AM
store@PDB1> selectcurrent_timestamp,localtimestamp,systimestamp from dual;
CURRENT_TIMESTAMP
---------------------------------------------------------------------------
LOCALTIMESTAMP
---------------------------------------------------------------------------
SYSTIMESTAMP
---------------------------------------------------------------------------
08-NOV-15 04.00.30.943720 PM -05:00
08-NOV-15 04.00.30.943720 PM
08-NOV-15 04.00.30.943702 PM -05:00
如果将TIME_ZONE设置为EST，
store@PDB1> alter session set time_zone='EST';
Session altered.
store@PDB1> selectcurrent_timestamp,localtimestamp,systimestamp from dual;
CURRENT_TIMESTAMP
---------------------------------------------------------------------------
LOCALTIMESTAMP
---------------------------------------------------------------------------
SYSTIMESTAMP
---------------------------------------------------------------------------
08-NOV-15 04.15.16.003530 PM EST
08-NOV-15 04.15.16.003530 PM
08-NOV-15 04.15.16.003520 PM -05:00
然后改回PST
store@PDB1> alter session set time_zone='PST';
Session altered.
store@PDB1> select extract(year fromto_date('01-jan-2008 19:15:26','dd-mon-yyyy hh24:mi:ss')) as year,
extract(month from to_date('01-jan-2008 19:15:26','dd-mon-yyyyhh24:mi:ss')) as month,
extract(day from to_date('01-jan-2008 19:15:26','dd-mon-yyyy hh24:mi:ss'))as day
from dual;
YEAR MONTH DAY
---------- ---------- ----------
2008 1 1
store@PDB1> select from_tz(timestamp '2008-05-1307:15:31.1234','-7:00') from dual;
FROM_TZ(TIMESTAMP'2008-05-1307:15:31.1234','-7:00')
---------------------------------------------------------------------------
13-MAY-08 07.15.31.123400000 AM -07:00
执行如下：
store@PDB1> select sys_extract_utc(timestamp'2008-11-17 19:15:26 pst') from dual;
SYS_EXTRACT_UTC(TIMESTAMP'2008-11-1719:15:26PST')
---------------------------------------------------------------------------
18-NOV-08 03.15.26.000000000 AM
执行如下：
store@PDB1> select to_timestamp('2008-05-1307:15:31.1234','YYYY-MM-DD HH24:MI:SS.FF') from dual;
TO_TIMESTAMP('2008-05-1307:15:31.1234','YYYY-MM-DDHH24:MI:SS.FF')
---------------------------------------------------------------------------
13-MAY-08 07.15.31.123400000 AM
执行如下：
store@PDB1> select to_timestamp_tz('2008-05-1307:15:31.1234 PST', 'YYYY-MM-DD HH24:MI:SS.FF TZR') from dual;
TO_TIMESTAMP_TZ('2008-05-1307:15:31.1234PST','YYYY-MM-DDHH24:MI:SS.FFTZR')
---------------------------------------------------------------------------
13-MAY-08 07.15.31.123400000 AM PST
store@PDB1> select to_timestamp_tz('2008-05-13 07:15:31.1234 -7:00','YYYY-MM-DDHH24:MI:SS.FF TZH:TZM') from dual;
TO_TIMESTAMP_TZ('2008-05-1307:15:31.1234-7:00','YYYY-MM-DDHH24:MI:SS.FFTZH:
---------------------------------------------------------------------------
13-MAY-08 07.15.31.123400000 AM -07:00
执行如下：
store@PDB1> select cast('13-JUN-08' as timestampwith local time zone) from dual;
CAST('13-JUN-08'ASTIMESTAMPWITHLOCALTIMEZONE)
---------------------------------------------------------------------------
13-JUN-08 12.00.00.000000 AM
使用CAST()将一个更复杂的字符串转换为TIMESTAMP WITH LOCAL TIME ZONE：
store@PDB1> selectcast(to_timestamp_tz('2008-05-13 07:15:31.1234 pst','yyyy-mm-dd hh24:mi:ss.fftzr') as timestamp with local time zone) from dual;
CAST(TO_TIMESTAMP_TZ('2008-05-1307:15:31.1234PST','YYYY-MM-DDHH24:MI:SS.FFT
---------------------------------------------------------------------------
13-MAY-08 07.15.31.123400 AM
store@PDB1> selectcast(to_timestamp_tz('2008-05-13 07:15:31.1234 est','yyyy-mm-dd hh24:mi:ss.fftzr') as timestamp with local time zone) from dual;
CAST(TO_TIMESTAMP_TZ('2008-05-1307:15:31.1234EST','YYYY-MM-DDHH24:MI:SS.FFT
---------------------------------------------------------------------------
13-MAY-08 05.15.31.123400 AM
欢迎转载，转载请标明出处： http://blog.csdn.net/notbaron/article/details/49745689
9i数据库引入了一种新特性，可以存储时间戳。时间戳可以存储世纪、四位年、月、日、时、分、秒。与DATE类型比，时间戳有以下优点：
n 时间戳可以存储秒的小数位
n 时间戳可以存储时区
1. 使用时间戳类型
1.1 使用TIMESTAMP类型
与其他类型类似，TIMESTAMP类型也可以用来在表中定义列。CREATE TABLE purchases_with_timestamp (
product_id INTEGER REFERENCES products(product_id),
customer_id INTEGER REFERENCES customers(customer_id),
made_on TIMESTAMP(4)
);
INSERT INTO purchases_with_timestamp (
product_id, customer_id, made_on
) VALUES (
1,1, TIMESTAMP '2005-05-13 07:15:31.1234'
);
查询如下：
store@PDB1> select * frompurchases_with_timestamp;
PRODUCT_ID CUSTOMER_ID MADE_ON
---------- --------------------------------------------------------------------------------------
1 1 13-MAY-05 07.15.31.1234 AM
1.2 使用TIMESTAMP WITH TIME ZONE类型
TIMESTAMP WITH TIME ZONE类型对TIMESTAMP进行了扩展，用于存储时区。CREATE TABLE purchases_timestamp_with_tz (
product_id INTEGER REFERENCES products(product_id),
customer_id INTEGER REFERENCES customers(customer_id),
made_on TIMESTAMP(4) WITH TIME ZONE
);
INSERT INTO purchases_timestamp_with_tz (
product_id, customer_id, made_on
) VALUES (
1,1, TIMESTAMP '2005-05-13 07:15:31.1234 -07:00'
);
查看如下内容：
store@PDB1> select * frompurchases_timestamp_with_tz;
PRODUCT_ID CUSTOMER_ID MADE_ON
---------- ----------- ---------------------------------------------------------------------------
1 1 13-MAY-05 07.15.31.1234 AM -07:00
1 2 13-MAY-05 07.15.31.1234 AM PST
1.3 使用TIMESTAMP WITH LOCAL TIME ZONE类型
TIMESTAMP WITH LOCAL TIME ZONE类型对TIMESTAMP进行了扩展，用于存储一个转换为数据库设置的本地时区的时间戳。如果企业已经实现了一个全球系统，可以通过世界各地访问，就应该使用TIMESTAMP WITH LOCAL TIME ZONE类型来存储时间戳。CREATE TABLE purchases_with_local_tz (
product_id INTEGER REFERENCES products(product_id),
customer_id INTEGER REFERENCES customers(customer_id),
made_on TIMESTAMP(4) WITH LOCAL TIME ZONE
);
INSERT INTO purchases_with_local_tz (
product_id, customer_id, made_on
) VALUES (
1,1, TIMESTAMP '2005-05-13 07:15:30 EST'
);
INSERT INTO purchases_with_local_tz (
product_id, customer_id, made_on
) VALUES (
2, 2,TIMESTAMP '2005-05-14 07:15:30 PST'
);
查看如下：
store@PDB1> select * from purchases_with_local_tz;
PRODUCT_ID CUSTOMER_ID MADE_ON
---------- --------------------------------------------------------------------------------------
2 2 14-MAY-05 09.15.30.0000 AM
1 1 13-MAY-05 07.15.30.0000 AM
2. 与时间戳有关的函数
2.1 CURRENT_TIMESTAMP、LOCALTIMESTAMP和SYSTIMSTAMP
执行如下：store@PDB1> selectcurrent_timestamp,localtimestamp,systimestamp from dual;
CURRENT_TIMESTAMP
---------------------------------------------------------------------------
LOCALTIMESTAMP
---------------------------------------------------------------------------
SYSTIMESTAMP
---------------------------------------------------------------------------
08-NOV-15 04.00.30.943720 PM -05:00
08-NOV-15 04.00.30.943720 PM
08-NOV-15 04.00.30.943702 PM -05:00
如果将TIME_ZONE设置为EST，
store@PDB1> alter session set time_zone='EST';
Session altered.
store@PDB1> selectcurrent_timestamp,localtimestamp,systimestamp from dual;
CURRENT_TIMESTAMP
---------------------------------------------------------------------------
LOCALTIMESTAMP
---------------------------------------------------------------------------
SYSTIMESTAMP
---------------------------------------------------------------------------
08-NOV-15 04.15.16.003530 PM EST
08-NOV-15 04.15.16.003530 PM
08-NOV-15 04.15.16.003520 PM -05:00
然后改回PST
store@PDB1> alter session set time_zone='PST';
Session altered.
2.2 EXTRACT函数
EXTRACT函数用于从x中提取并返回年、月、日、时、分、秒或时区。store@PDB1> select extract(year fromto_date('01-jan-2008 19:15:26','dd-mon-yyyy hh24:mi:ss')) as year,
extract(month from to_date('01-jan-2008 19:15:26','dd-mon-yyyyhh24:mi:ss')) as month,
extract(day from to_date('01-jan-2008 19:15:26','dd-mon-yyyy hh24:mi:ss'))as day
from dual;
YEAR MONTH DAY
---------- ---------- ----------
2008 1 1
2.3 FROM_TZ()
FROM_TZ(x,time_zone)将TIMESTAMP类型的x转换为由time_zone指定的时区，并返回TIMESTAMPWITH TIMEZONE类型。TIME_ZONE必须被指定为+|- HH:MI格式的字符串。store@PDB1> select from_tz(timestamp '2008-05-1307:15:31.1234','-7:00') from dual;
FROM_TZ(TIMESTAMP'2008-05-1307:15:31.1234','-7:00')
---------------------------------------------------------------------------
13-MAY-08 07.15.31.123400000 AM -07:00
2.4 SYS_EXTRACT_UTC()
SYS_EXTRACT_UTC(x)用于将TIMESTAMPWITH TIMEZONE类型的x转换为一个包含UTC时区日期和时间的TIMESTAMP类型。执行如下：
store@PDB1> select sys_extract_utc(timestamp'2008-11-17 19:15:26 pst') from dual;
SYS_EXTRACT_UTC(TIMESTAMP'2008-11-1719:15:26PST')
---------------------------------------------------------------------------
18-NOV-08 03.15.26.000000000 AM
2.5 TO_TIMESTAMP()
TO_TIMESTAMP(x, [format])用于将字符串 x 转换为一个TIMESTAMP类型。执行如下：
store@PDB1> select to_timestamp('2008-05-1307:15:31.1234','YYYY-MM-DD HH24:MI:SS.FF') from dual;
TO_TIMESTAMP('2008-05-1307:15:31.1234','YYYY-MM-DDHH24:MI:SS.FF')
---------------------------------------------------------------------------
13-MAY-08 07.15.31.123400000 AM
2.6 TO_TIMESTAMP_TZ()
TO_TIMESTAMP_TZ(x, [ format ])用于将字符串x转换为一个TIMESTAMP WITH TIMEZONE类型。执行如下：
store@PDB1> select to_timestamp_tz('2008-05-1307:15:31.1234 PST', 'YYYY-MM-DD HH24:MI:SS.FF TZR') from dual;
TO_TIMESTAMP_TZ('2008-05-1307:15:31.1234PST','YYYY-MM-DDHH24:MI:SS.FFTZR')
---------------------------------------------------------------------------
13-MAY-08 07.15.31.123400000 AM PST
store@PDB1> select to_timestamp_tz('2008-05-13 07:15:31.1234 -7:00','YYYY-MM-DDHH24:MI:SS.FF TZH:TZM') from dual;
TO_TIMESTAMP_TZ('2008-05-1307:15:31.1234-7:00','YYYY-MM-DDHH24:MI:SS.FFTZH:
---------------------------------------------------------------------------
13-MAY-08 07.15.31.123400000 AM -07:00
2.7 将字符串转换为TIMESTAMP WITH LOCAL TIME ZONE
将CAST函数可以将一个字符串转换为TIMESTAMP WITH LOCAL TIME ZONE。执行如下：
store@PDB1> select cast('13-JUN-08' as timestampwith local time zone) from dual;
CAST('13-JUN-08'ASTIMESTAMPWITHLOCALTIMEZONE)
---------------------------------------------------------------------------
13-JUN-08 12.00.00.000000 AM
使用CAST()将一个更复杂的字符串转换为TIMESTAMP WITH LOCAL TIME ZONE：
store@PDB1> selectcast(to_timestamp_tz('2008-05-13 07:15:31.1234 pst','yyyy-mm-dd hh24:mi:ss.fftzr') as timestamp with local time zone) from dual;
CAST(TO_TIMESTAMP_TZ('2008-05-1307:15:31.1234PST','YYYY-MM-DDHH24:MI:SS.FFT
---------------------------------------------------------------------------
13-MAY-08 07.15.31.123400 AM
store@PDB1> selectcast(to_timestamp_tz('2008-05-13 07:15:31.1234 est','yyyy-mm-dd hh24:mi:ss.fftzr') as timestamp with local time zone) from dual;
CAST(TO_TIMESTAMP_TZ('2008-05-1307:15:31.1234EST','YYYY-MM-DDHH24:MI:SS.FFT
---------------------------------------------------------------------------
13-MAY-08 05.15.31.123400 AM
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