Oracle當前日期前後推算公式

平時在專案中會經常遇到需要用某個日期（如當前系統時間）來獲取該日期前後的特定日期，下面列出一些常用的公式。

✳ sysdate為系統當前日期

基礎函式

select to_date('2016-06-15','yyyy-mm-dd') from dual -- 2016-6-15

select to_char(sysdate,'yyyy-mm-dd') from dual -- 系統當前日期

select trunc(to_date('2016-06-15','yyyy-mm-dd'),'year') from dual -- 2016-1-1

select add_months(trunc(to_date('2016-06-15','yyyy-mm-dd'),'year'),12)-1

from dual -- 2016-12-31

select

add_months(last_day(to_date('2016-06-15','yyyy-mm-dd'))+1,-2) from dual -- 2016-5-1
select
add_months(last_day(to_date('2016-01-15','yyyy-mm-dd'))+1,-2) from dual -- 2015-12-1

select

add_months(last_day(to_date('2016-06-15','yyyy-mm-dd')),-1) from dual -- 2016-5-31
select
add_months(last_day(to_date('2016-01-15','yyyy-mm-dd')),-1) from dual -- 2015-12-31

select

trunc(to_date(add_months(last_day(to_date('2016-06-15','yyyy-mm-dd')),-1)),'year') from dual -- 2016-1-1
select
trunc(to_date(add_months(last_day(to_date('2016-01-15','yyyy-mm-dd')),-1)),'year') from dual -- 2015-1-1

select

add_months(trunc(to_date(add_months(last_day(to_date('2016-06-15','yyyy-mm-dd')),-1)),'year'),12)-1 from dual -- 2016-12-31
select
add_months(trunc(to_date(add_months(last_day(to_date('2016-01-15','yyyy-mm-dd')),-1)),'year'),12)-1 from dual -- 2015-12-31

select add_months(trunc(to_date('2016-06-15','yyyy-mm-dd'),'year'),-12) from dual -- 2015-1-1

select trunc(to_date('2016-06-15','yyyy-mm-dd'),'year')-1

from dual -- 2015-12-31

select

add_months(last_day(to_date('2016-06-15','yyyy-mm-dd'))+1,0) from dual -- 2016-7-1
select
add_months(last_day(to_date('2015-12-15','yyyy-mm-dd'))+1,0) from dual -- 2016-1-1

select

add_months(last_day(to_date('2016-06-15','yyyy-mm-dd')),1) from dual -- 2016-7-31
select
add_months(last_day(to_date('2015-12-15','yyyy-mm-dd')),1) from dual -- 2016-1-31

select

trunc(to_date(add_months(last_day(to_date('2016-06-15','yyyy-mm-dd')),1)),'year') from dual -- 2016-1-1
select
trunc(to_date(add_months(last_day(to_date('2015-12-15','yyyy-mm-dd')),1)),'year') from dual -- 2016-1-1

select

add_months(trunc(to_date(add_months(last_day(to_date('2016-06-15','yyyy-mm-dd')),1)),'year'),12)-1 from dual -- 2016-12-31
select
add_months(trunc(to_date(add_months(last_day(to_date('2015-12-15','yyyy-mm-dd')),1)),'year'),12)-1 from dual -- 2016-12-31

select add_months(trunc(to_date('2016-06-15','yyyy-mm-dd'),'year'),12) from dual -- 2017-1-1

select add_months(trunc(to_date('2016-06-15','yyyy-mm-dd'),'year')-1,24) from dual -- 2017-12-31

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