sql/php - add 4 days to unixtimestamps, with different starting days

Question

I have a database with 30k+ users. I wish to add 4 days to a time I have stored for each user in unixtimestamp.

The time represent when they have joined, therefore each timestamp is different than the other.

Can I, simply, add 4 days to ALL of these timestamp via. SQL?

Answer 1

Yes you can

UPDATE yourtable SET yourfield = yourfield + 345600

or you calculate it directly in your query.

UPDATE yourtable SET yourfield = yourfield + (60*60*24*4)

But you should make some tests before.

Answer 2

Try with INTERVAL 4 DAYS like this

UPDATE tbl_name set time_col = DATE_ADD(time_col, INTERVAL 4 DAY);

Answer 3

You do it using single UPDATE query. Try this

UPDATE `users` SET time = time+(86400*4);