SQL TO_DATE格式错误

Question

I wrote this statement to get the 1st day of the previous month

select '01.' || TO_CHAR(ADD_MONTHS(SYSDATE,-1),'MM.yyyy') from dual

Output: 01.02.2016

If I use TO_DATE to format I get the following error: not a valid month

My current not working solution:

select TO_DATE('01.' || TO_CHAR(ADD_MONTHS(SYSDATE,-1),'MM.yyyy')) from dual

Thanks for any help / advices

Answer 1

You need a format String for to_date, too:

select TO_DATE('01.' || TO_CHAR(ADD_MONTHS(SYSDATE,-1),'MM.yyyy'), 'dd.mm.yyyy') from dual

But it is simpler to use trunc, as proposed by lad2025.

Answer 2

You could calculate it using TRUNC :

SELECT TRUNC(ADD_MONTHS(SYSDATE,-1),'mm') AS result
FROM dual;