how to generate unique id in php based on current data and time?

Question

I need to generate a unique ID in php based on current date and time to keep a log of when i am running code. i.e. every time i run the code it should be able to generate a unique id based on current date and time.

Hope I am clear with my ques. How to do that?

Solution 1

Using time() to create sortable unique id's

Concatenating strings will also further randomize your desired result and still keep it sortable. manual here

$uniqueId= time().'-'.mt_rand();

Solution 2

You can use a combination of uniqid() and time() like so:

$s = uniqid(time(), true);

Example output:

1346136883503c6b3330caf5.19553126

Solution 3

Is this what you're looking for? uniqid()

From the doc:

Gets a prefixed unique identifier based on the current time in microseconds.

Comments

[user1518659]

will it generate uniqueid() based on time only?? if so what happens if there is a time conflict...i am not clear.. i need a manual code that generates unique id every time i run the code @Mythril

[Álvaro González]

You'll possibly get the same ID if your IDs are generated on the same microsecond. It's difficult but could happen. You can make it harder by appending a random string--the base technique is good IMHO.

[Lucas Green]

php.net/manual/en/function.uniqid.php the doc indicates that you can provide a prefix and an entropy source.

[user1518659]

what do they mean by prefix string? I dont get it.. entropy too.. @Mythril

[Lucas Green]

A prefix is an arbitrary string that you provide to give the id extra meaning/differentiate it (it's up to you really). An entropy source is just an additional number (preferably random or pseudo-random) that will make the id less likely to collide with previously generated ids.

[user1518659]

have you tried 'time().'-'.mt_rand();'.. can you ensure uniqid() gives a better result than this? i mean what is the best way.. no offence.

[amitchhajer]

do you want to store Id's in sorted order?

[Breith]

We can also complexify the generation of a unique id with the function md5 md5(uniqid(time(), true)).