我正在尝试编写查询以返回给定区域的当前缩写时区。例如...
“美国/纽约” 'America / Los_Angeles'
我希望将它们转换为...
'EDT' “ PDT”
我可以使用本地时区实现
select TO_CHAR(CAST(SYSDATE AS TIMESTAMP WITH LOCAL TIME ZONE),'TZD') from dual;
哪个返回“ PDT”。但是我需要它来返回任何区域的时区。希望有类似...
select TO_CHAR(CAST(SYSDATE AS TIMESTAMP AT TIME ZONE 'America/Los_Angeles'),'TZD') from dual;
但是Oracle不喜欢这种语法。知道如何获得它吗？
答案 0 :(得分：3)
AT TIME ZONE是一个时间戳修饰符，不属于CAST表达式。
因此：
select to_char(cast(sysdate as timestamp) at time zone 'America/Los_Angeles', 'TZD')
from dual;
或更简单：
select to_char(systimestamp at time zone 'America/Los_Angeles', 'TZD') from dual;
这是获取所有当前时区的查询：
select distinct tzname, to_char(systimestamp at time zone tzname, 'TZD') as zone
from v$timezone_names
order by tzname;
答案 1 :(得分：0)
您认为什么是“缩写时区”？时区缩写没有通用的标准，并且其中许多没有区别，请参见Time zone Abbreviations或以下示例：
SELECT tzname, tzabbrev
FROM v$timezone_names
WHERE tzname = 'America/Los_Angeles';
+----------------------------+
|TZNAME |TZABBREV|
+----------------------------+
|America/Los_Angeles|LMT |
|America/Los_Angeles|PST |
|America/Los_Angeles|PDT |
|America/Los_Angeles|PWT |
|America/Los_Angeles|PPT |
+----------------------------+
反之亦然：
SELECT tzname, tzabbrev, TZ_OFFSET(tzname)
FROM v$timezone_names
WHERE tzabbrev = 'EST'
order by 3;
+----------------------------------------------+
|TZNAME |TZABBREV|TZ_OFFSET(TZNAME)|
+----------------------------------------------+
|Australia/Yancowinn|EST |+09:30 |
|Australia/Broken_Hi|EST |+09:30 |
|Australia/ACT |EST |+10:00 |
|Australia/Brisbane |EST |+10:00 |
|Australia/Canberra |EST |+10:00 |
|Australia/Queenslan|EST |+10:00 |
|Australia/Hobart |EST |+10:00 |
|Australia/Lindeman |EST |+10:00 |
|Australia/Victoria |EST |+10:00 |
|Australia/Melbourne|EST |+10:00 |
|Australia/NSW |EST |+10:00 |
|Australia/Tasmania |EST |+10:00 |
|Australia/Sydney |EST |+10:00 |
|Australia/Currie |EST |+10:00 |
|Australia/Lord_Howe|EST |+10:30 |
|Australia/LHI |EST |+10:30 |
|Antarctica/Macquari|EST |+11:00 |
|America/Moncton |EST |-03:00 |
|America/Antigua |EST |-04:00 |
|America/Detroit |EST |-04:00 |
|America/Fort_Wayne |EST |-04:00 |
|America/Grand_Turk |EST |-04:00 |
|America/Indiana/Ind|EST |-04:00 |
|America/Indiana/Mar|EST |-04:00 |
|America/Indiana/Pet|EST |-04:00 |
|America/Indiana/Vev|EST |-04:00 |
|America/Indiana/Vin|EST |-04:00 |
|America/Indiana/Win|EST |-04:00 |
|America/Indianapoli|EST |-04:00 |
|America/Iqaluit |EST |-04:00 |
|America/Kentucky/Lo|EST |-04:00 |
|America/Kentucky/Mo|EST |-04:00 |
|America/Louisville |EST |-04:00 |
|America/Montreal |EST |-04:00 |
|America/Nassau |EST |-04:00 |
|America/New_York |EST |-04:00 |
|America/Nipigon |EST |-04:00 |
|America/Pangnirtung|EST |-04:00 |
|America/Santo_Domin|EST |-04:00 |
|America/Thunder_Bay|EST |-04:00 |
|America/Toronto |EST |-04:00 |
|Canada/Eastern |EST |-04:00 |
|EST5EDT |EST |-04:00 |
|US/East-Indiana |EST |-04:00 |
|US/Eastern |EST |-04:00 |
|US/Michigan |EST |-04:00 |
|US/Central |EST |-05:00 |
|Jamaica |EST |-05:00 |
|America/Cancun |EST |-05:00 |
|America/Cayman |EST |-05:00 |
|America/Chicago |EST |-05:00 |
|America/Coral_Harbo|EST |-05:00 |
|America/Indiana/Kno|EST |-05:00 |
|America/Indiana/Tel|EST |-05:00 |
|America/Jamaica |EST |-05:00 |
|America/Knox_IN |EST |-05:00 |
|America/Atikokan |EST |-05:00 |
|America/Menominee |EST |-05:00 |
|America/Merida |EST |-05:00 |
|America/Panama |EST |-05:00 |
|America/Port-au-Pri|EST |-05:00 |
|America/Rankin_Inle|EST |-05:00 |
|America/Resolute |EST |-05:00 |
|CST |EST |-05:00 |
|EST |EST |-05:00 |
|US/Indiana-Starke |EST |-05:00 |
|America/Managua |EST |-06:00 |
|America/Cambridge_B|EST |-06:00 |
+----------------------------------------------+
注意，TZD的结果不仅取决于地区，而且取决于时间：
SELECT
TO_CHAR(SYSTIMESTAMP AT TIME ZONE 'America/Los_Angeles', 'TZD') AS ZTD_SUMMER,
TO_CHAR((SYSTIMESTAMP + NUMTODSINTERVAL(150, 'DAY')) AT TIME ZONE 'America/Los_Angeles', 'TZD') as ZTD_WINTER
FROM dual;
+------------------------------+
|ZTD_SUMMER |ZTD_WINTER|
+------------------------------+
|PDT |PST |
+------------------------------+