date comparisons

jonsof

i have a date "12-30-2002" and another one "30-01-2003".
I want to compare them each other.

How can i do that?

altexis

gia sou re gianni

these two dates are obviously of different format!!
12-30-2002 is Month-Day-Year, whereas
30-01-2003 is Day-Month-Year

So I guess it is hard for php to know what format it has to choose at any given time.

There is the strtotime() function and you could compare the two dates by subtracting two dates after you have filtered them with strtotime()

However since europeans always have problems with american dates... I would suggest you to format all your dates to Year-Month-Day which is very handy because this way you can even compare two dates even as strings

jonsof

Gia sou altexis 🙂

I put the following code

echo strtotime("12-30-2002");
echo strtotime("30-01-2003");

And the results are 1574460000 and 2066418000 respectively.
Are these the time in seconds?

So can i compare these results directly?

Weedpacket

They're the number of seconds elapsed since the start of January 1st, 1970. At least, they're supposed to be; the second number is way off - by about two or three decades if my estimate is right.

I guess that's what happens when you use ambiguous date formats.

Mezza

Comparing these two dates is pretty simple ...

To compare 2 dates ( or dates and times ) you first need to convert them into a UNIX timestamp, which, as weedpacket said, is the number of seconds since some time in 1970.

Basically, take your two dates, and do the following...

<?
echo mktime (0, 0,0 ,0, 00,0000 );
?>

thats hours,minutes,seconds,month,day,year

So for your two dates you would use...

// 30-01-2003
echo mktime (0, 0,0 ,1, 30,2003 );

// 12-30-2002
echo mktime (0, 0,0 ,12, 30,2002 );

From this, you will have two UNIX timestamps, which u can include in any calculation you like, i.e subtracting a day would be

unixstamp - 86400 (60 seconds 60 minutes 24 hours)

Or to get the difference, subtract one from the other.

To convert the time stamp back to the format of your choice, use the strftime ("%m/%d/%Y" ,YOURNEWTIMESTAMP);

which would give you your date in the format dd/mm/yyyy

check out http://www.php.net/manual/en/function.date.php for a full list of the date formats

jonsof

now my problem is that :

$today = getdate();
echo $crucial_date = strftime("%m-%d-%Y",mktime(0,0,0,$today['mon']-1,$today['mday'],$today['year']));

$today="12-30-2002";

and the other date (is being formated as dd-mm-yy through SQL syntax) comes from a table in a loop.

Therefore, what can i do in that case? I have tried several ways but i didn't get the result i wanted.

I want to test if the $today date is equal to one of the dates contained in the table and then to echo a <hr>.

I don;t know where is my fault 🙁

Mezza

So, if i am correct, you are trying to compare a date in a Database (already in the format mm/dd/yyy)

What you are best to do, is store the date as a unix timestamp in the database, then convert it everytime u pull it out.

so your script would be as below:

// Get todays date ...

$today = getdate();
$the_date $crucial_date = strftime("%m-%d-%Y",mktime(0,0,0,$today['mon']-1,$today['mday'],$today['year']));

// Query the database

$date_query = mysql_query("SELECT datefield FROM datetable);
$date_vars = mysql_fetch_array($date_query);

// loop compare

do {

// Compare all dates in the datetable to todays date, if date is equal, echo it to the screen

if($the_date == $query_vars[date]) {
echo "<hr>$query_vars[date])";
}

} while ($date_vars = mysql_fetch_array($date_query));

jonsof

Is there another way to do my job?

should i have a datestamp field in my database and compare the date stamp of php?

Mezza

I think your problem is the date format you use, you should either change the date format to something strtotime() can use, or store it as a timestamp in your database, i don't know of any other way.

jonsof

i created a table which contains a timestamp field. and i put now() in order to take the current timestamp=20030130133051.

i put this code

echo strftime("%m-%d-%Y",$row[0]);

which $row[0] is the field marked as timestamp.

and the result is : 01-19-2038 🙁🙁

Why that?

Mezza

The now() MySQL command returns the datestamp as such:

yyy-mm-dd hh:mm:ss

it does nto return a unix timestamp, therefore for the stamp you have 20030130133051 = 2003-01-30 13:30:51

You need to use unix_timestamp() instead of now.

Keep in mind, unix_timestamp and now() return the current date and time, just use a standard mySQL fetch command to return the timestamp you have stored.

jonsof

I crated the field and i insert a unix_timestamp,
The result is 20001116001732

How can i transform this into a form ("dd-mm-yy")

Weedpacket

That number doesn't look like a Unix timestamp

20001116001732

It looks like a MySQL timestamp for 2000-11-16, 00:17:32.

jonsof

but in fact i use the unix_timestamp for mysql!

Mezza

Yes, that number is a standard mysql timestamp, try using phps unix timestamping (as I have outlined above). It is much simpler if you allow php to convert the date at both ends (going into the database, and coming back out)

jonsof

in that case i must use a field which is not date type but is a VARCHAR(20).

Mezza

Yeah, use a varchar, sorry I didn't know you were using a date field 🙂

Goodluck!

Weedpacket

Er, no; you'd be storing an integer, so you'd be using an integer field, not a varchar.

jonsof

What is the difference? Only memory?

altexis

Originally posted by jonsof
I crated the field and i insert a unix_timestamp,
The result is 20001116001732

How can i transform this into a form ("dd-mm-yy")

$timestamp = "20001116001732";

$year = (int) substr($timestamp, 0, 4);
$month = (int) substr($timestamp, 4, 2);
$day = (int) substr($timestamp, 6, 2);
$hour = (int) substr($timestamp, 8, 2);
$min = (int) substr($timestamp, 10, 2);
$sec = (int) substr($timestamp, 12, 2);