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.
Domanda
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?
Soluzione
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.
Altri suggerimenti
Try with INTERVAL 4 DAYS like this
UPDATE tbl_name set time_col = DATE_ADD(time_col, INTERVAL 4 DAY);
You do it using single UPDATE
query. Try this
UPDATE `users` SET time = time+(86400*4);