sql update random between two dates

Question

I've tried to update my database and changing dates. I've done some research but I did not found any issue. So I used two timestamp.

I've tried to do that method:

UPDATE `ps_blog_post` 
SET `time_add` = ROUND((RAND() * (1387888821-1357562421)+1357562421))

Now everywhere the new date is:

0000:00:00

Anykind of help will be much appreciated

Answer 1

Try this one to get timestamp between two timestamps

SET @MIN = '2013-01-07 00:00:00';
SET @MAX = '2013-12-24 00:00:00';

UPDATE `ps_blog_post` 
SET `time_add` =  TIMESTAMPADD(SECOND, FLOOR(RAND() * TIMESTAMPDIFF(SECOND, @MIN, @MAX)), @MIN);

Fiddle

Answer 2

You have the right idea, your conversion from the int literals you're using back to the timestamp seems off though - you're missing an explicit call to FROM_UNIXTIME:

UPDATE `ps_blog_post` 
SET `time_add` = 
     FROM_UNIXTIME(ROUND((RAND() * (1387888821 - 1357562421) + 1357562421)))