Subtract 30 days to a date

[storm197]

Hi,

I want to do a thing I thought would be simple.

I have a date, example : 2004-10-15 11:17:42

I want to subtract 30 days from it (a month)

Result I want: 2004-09-15 11:17:42

Can anyone help me? I tried to use the mktime function, but it gives me a result like 1097899200

 

[cLFlaVA]

$date = date("Y-m-d", mktime(0, 0, 0, date("m") - 1, date("d"), date("Y")));

*cLFlaVA
----------------------------
Lois: "Peter, you're drunk!"
Peter: "I'm not drunk, I'm just exhausted from stayin' up all night drinking!

 

[kenrbnsn]

Here's another way:

<?
$date = '2004-10-15 11:17:42';
echo date('Y-m-d g:i:s a',strtotime("-30 days"))."\n"; //Thirty days before 'now'
echo date('Y-m-d g:i:s a',strtotime("-30 days",strtotime($date)))."\n"; //Thirty days before the given date
?>

Ken

 

[storm197]

Thanks guys! everything is working fine!

 

[ericbrunson]

cflava, does that work for January?

 

[cLFlaVA]

Ahh, great question!

To be sure, maybe I should re-post as this:

$date = date("Y-m-d", mktime(0, 0, 0, date("m") < 1 ? 12 : date("m") - 1, date("d"), date("Y")));

or, neater, but one more line of code:

$m = date("m") < 1 ? 12 : date("m") - 1;
$date = date("Y-m-d", mktime(0, 0, 0, $m, date("d"), date("Y")));

Thanks for pointing that out [blue]eb[/blue].

*cLFlaVA
----------------------------
Lois: "Peter, you're drunk!"
Peter: "I'm not drunk, I'm just exhausted from stayin' up all night drinking!

 

[flubbard]

I believe the cLFlaVA would work and give you the right year (instead of giving some funny 0th month, it would update the year and the month), I will check again...just a thought

Flub

 

[Olavxxx]

I know this is not what you asked for, but if you want to do the same in a mysql query:

http://dev.mysql.com/doc/mysql/en/Date_and_time_functions.html

it's very simple in mysql! If you retrieve data, I think it's also faster to make the sql do something with the result, rather than doing it in php.

 

[ericbrunson]

I actually make MySQL do all my date calculations, even if I don't use the database for storage.

Oracle has a nice little convention of always having a table called 'dual' that has one row with one column in it. It allows you to write queries like "select username from dual" or "select sysdate from dual". Both username and sysdate are pseudo-columns.

I create the same thing in a database in mysql and grant select to a user with no password, so I can do "select date_sub( now(), interval 30 day) from dual" and I always get one row returned.