[oracle] SQL Query to fetch data from the last 30 days?

Hi I am new to Oracle. How do I do a simple statement, for example get product id from the last 30, or 20 days purchase date?

SELECT productid FROM product
WHERE purchase_date ? 

Try this : Using this you can select data from last 30 days

SELECT
    *
FROM
    product
WHERE
    purchase_date > DATE_SUB(CURDATE(), INTERVAL 1 MONTH)

SELECT COUNT(job_id) FROM jobs WHERE posted_date < NOW()-30;

Now() returns the current Date and Time.

Pay attention to one aspect when doing "purchase_date>(sysdate-30)": "sysdate" is the current date, hour, minute and second. So "sysdate-30" is not exactly "30 days ago", but "30 days ago at this exact hour".

If your purchase dates have 00.00.00 in hours, minutes, seconds, better doing:

where trunc(purchase_date)>trunc(sysdate-30)

(this doesn't take hours, minutes and seconds into account).

The easiest way would be to specify

SELECT productid FROM product where purchase_date > sysdate-30;

Remember this sysdate above has the time component, so it will be purchase orders newer than 03-06-2011 8:54 AM based on the time now.

If you want to remove the time conponent when comparing..

SELECT productid FROM product where purchase_date > trunc(sysdate-30);

And (based on your comments), if you want to specify a particular date, make sure you use to_date and not rely on the default session parameters.

SELECT productid FROM product where purchase_date > to_date('03/06/2011','mm/dd/yyyy')

And regardng the between (sysdate-30) - (sysdate) comment, for orders you should be ok with usin just the sysdate condition unless you can have orders with order_dates in the future.

select status, timeplaced 
from orders 
where TIMEPLACED>'2017-06-12 00:00:00'