Oracle日期提取和连接

Question

I have to take a date ( dd-mon-yyyy ) and change the year based on a user input. How do I extract the day and month and add the year while keeping the format?

For example, it is currently 01-JAN-2015 , and the user wants it to be 01-JAN-2016 . I currently am doing:

SELECT EXTRACT(DAY FROM contract_year) || EXTRACT(MONTH FROM contract_year) || '2016'
FROM table
WHERE program = programid

And my output is 112016 , but I want 01-JAN-2016 . Any suggestions?

Answer 1

Try this

SELECT to_char(add_months('01-JAN-2015', 12*1),'dd-MON-yyyy') -- replace 1 with n where n = years
from dual

If you want to add use given year to current date/month, use this

      with your_table as(
      select '01-JAN-2015' as contract_year from dual
      )
      select to_date(substr(to_char(contract_year),1,7)||'2017','DD-MON-YYYY') from your_table

If your are not seeing output as required, it means that you have to change your client setting. Try running this in SQL Plus window.

Answer 2

Combine to_date and to_char:

SELECT to_date(to_char(contract_year,'dd-mm-') || '2016','dd-mm-yyyy')
FROM table
WHERE program = programid

Answer 3

It's not entirely clear to me whether contract_year is a date or a string.

If it's a date:

select to_char(contract_year, 'DD-MON-') || '2016'
  from table

If it's a string in the format DD-MON-YYYY then:

select to_char(to_date(contract_year, 'DD-MON-YYYY'), 'DD-MON-') || '2016'
  from table