When to use the ROUND function in oracle

Question

I want to store a time value in a table using the Date date format in oracle.
I also want to store it to the nearest hour using the round function. eg 1700, 1800
When exactly do I use the round function to do this? When defining the table type? or when creating the table? Or when using the INSERT command?

Answer 1

Do it on the insert:

INSERT INTO your_table (date_col) VALUES (ROUND(SYSDATE,'HH'));

You can use any arbitrary date value, I used SYSDATE for simplicity.

Answer 2

Use round(<datetime>, 'HH') . Example:

select round( to_date('2012-01-01 12:30','yyyy-mm-dd hh24:mi')
            , 'HH')
from dual