Oracle：在日期时间过滤查询

Question

I need to restrict a query with a

SELECT ... FROM ... 
WHERE my_date=(RESULT FROM A SELECT)
...  ;

in order to achieve that I am using as result of the select a timestamp (if I instead use a datetime I get nothing from my select probably because the format I am using trims the datetime at the second).

Sadly this is not working because these kindo of queries:

select DISTINCT TO_DATE(TO_TIMESTAMP(TO_DATE('25-10-2017 00:00', 'dd-MM-yyyy HH24:MI'))) from DUAL;

return an

ORA-01830: date format picture ends before converting entire input string

how to deal with timestamp to date conversion?

Answer 1

If you want to just compare and check only he dates use trunc on both LHS and RHS.

SELECT ... FROM ... 
WHERE trunc(my_date)=(select trunc(RESULT) FROM A)
...  ;

This will just compare the dates by truncating the timestamp values

Answer 2

You can use the combination of "TRUNC" and "IN" keywords in your query to achieve what you are expecting. Please check the below query sample as a reference.

SELECT * FROM customer WHERE TRUNC(last_update_dt) IN (select DISTINCT (TRUNC(last_update_dt)) from ... )

Cheers !!