I'm currently searching for a good way to generate a unique random number for SEPA transactions (End-to-End reference) with 27 digits in PHP. My requirements are:
Must be unique
Only int values, no letters
Length of 27 digits
Use an user id and time to make the ID unique
I've tried this solution here but this only gives me a string with letters and numbers:
md5( uniqid( mt_rand(), true ) );
Does anyone has a lightweight solution or idea?
echo $bira = date('YmdHis').rand(1000000000000,9000000000000);
echo "<br/>";
echo strlen($bira);
Add the time stamp in the front, so it will be unique always.
OR echo $bira = time().rand(10000000000000000,90000000000000000);
outoput:
201901220142532979656312614
27
How about this:
$array = [];
$numberOfTransactions = 1;
while (count($array) < $numberOfTransactions) {
$rand = mt_rand(100000000000000000000000000, 999999999999999999999999999);
$array[$rand] = $rand;
}
print_r($array);
Associative array keys are unique, so you won't get any duplicates.
Related
I am generating random numbers using php random function, but I want the generated number should be unique and it should not be repeated again.
----------
php code
$number = rand(100,100000); //a six digit random number between 100 to 100000
echo $number;
----------
but I am using this function for multiple times in my code for users so at very rare case there should be a chance of generating same number again. how can i avoid that.
I would do this:
You said you have branches. The receipt id could look something like this:
$dateString = date('Ymd'); //Generate a datestring.
$branchNumber = 101; //Get the branch number somehow.
$receiptNumber = 1; //You will query the last receipt in your database
//and get the last $receiptNumber for that branch and add 1 to it.;
if($receiptNumber < 9999) {
$receiptNumber = $receiptNumber + 1;
}else{
$receiptNumber = 1;
}
Update the receipt database with the receipt number.
$dateString . '-' . $branchNumber . '-' . $receiptNumber;
This will read:
20180406-101-1
This will be unique(Provided you do less than 10,000 transactions a day.) and will show your employees easily readable information.
If you are storing users in DB you should create column [ID] as primary key with auto increment and that would be best solution.
In other case I'd recommend you to simply store all user id's in ascending order from N to M by reading last ID and adding 1 to it because I see no real gain from random order that only adds complexity to your code.
There are many ways, example:
$freq = [];
$number = rand(100,100000);
$times = 10;
while($times-- > 0)
{
while(in_array($number, $freq))$number = rand(100,100000);
$freq[] = $number;
echo $number . "<br>";
}
This will print 10 random unique numbers.
random_int
(PHP 7)
<?php
$number = random_int(100, 100000);
echo $number;
All you need to do is use timestamp in php as timestamp never cross each other hence it will always generate unique number.You can use time() function in php.
The time() function is used to format the timestamp into a human desired format. The timestamp is the number of seconds between the current time and 1st January, 1970 00:00:00 GMT. It is also known as the UNIX timestamp.
<?php
$t=time();
echo $t;
?>
Also you add a rand() function and insert it in front of the $t to make it more random as if few users work at same time then the timestamp might collide.
<?php
$number = rand(100,100000);
$t=time();
$random = $number.''.$t;
echo $random;
?>
The above will reduce the chance to timestamp collide hence making the probability of number uniqueness almost 100%.
And if you make your column unique in your database then the php wont insert the number hence this bottleneck will ensure you will always get a unique random number.
bill_id not null unique
If you are using it for something like user id, then you can use uniqid for that. This command gets a prefixed unique identifier based on the current time in microseconds.
Here's how to use it:
string uniqid ([ string $prefix = "" [, bool $more_entropy = FALSE]] )
Where prefix is used if you are generating ids for a lot if hosts at the same time, you can use this to differentiate between various hosts if id is generated at the same microsecond.
more_entropy increases the likeness of getting unique values.
Usage:
<?php
/* A uniqid, like: 4b3403665fea6 */
printf("uniqid(): %s\r\n", uniqid());
/* We can also prefix the uniqid, this the same as
* doing:
*
* $uniqid = $prefix . uniqid();
* $uniqid = uniqid($prefix);
*/
printf("uniqid('php_'): %s\r\n", uniqid('php_'));
/* We can also activate the more_entropy parameter, which is
* required on some systems, like Cygwin. This makes uniqid()
* produce a value like: 4b340550242239.64159797
*/
printf("uniqid('', true): %s\r\n", uniqid('', true));
?>
this code must work
some description about code:
generate unique id
extract numbers form unique id with regex
gathering numbers from regex with a loop
<?php
$unique = uniqid("",true);
preg_match_all("!\d+!", $unique ,$matches);
print_r($matches);
$numbers = "";
foreach($matches[0] as $key => $num){
$numbers .= $num;
}
echo $numbers;
I wonder if there is a way in PHP to generate a unique alphanumeric(case sensitive) tokens that can be unique forever without any collision. If we derive them from the time stamp string which is 10 characters like: 1394452319, that might be possible but I am not sure if we can make the token short up to 4 characters? If not possible then 5, 6, 7 and max is 8 characters. Because I want to generate short tokens to be readable by users.
Tokens should look like: 1aYc, ZoXq, 3iU9, etc.
I don't want to show the users any sequence.
One more thing, my application will be used by more than one user, so in case two users clicked at same time to generate the token, will the PHP application generate the same token (I assume we use the timestamp to generate the token)? How can we prevent from this problem?
Thank you for your help!
this is the another function that you can use also
<?php
function generateRandomString($length = 8) {
$characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
$randomString = '';
for ($i = 0; $i < $length; $i++) {
$randomString .= $characters[rand(0, strlen($characters) - 1)];
}
return $randomString;
}
echo generateRandomString();
?>
One approach is to have an incremental (i.e. auto_update) id that you keep hidden internally. From that, you generate a hash, representing the id to hide the sequence. The incremented id gets rid of collision problems (i.e. MySQL has an integrated solution for this).
The trick you need to use now is a random hash table consinsting of two columns, both having the values n to m but with the second column being randomized. i.e.
col1 | col2
1 | 2
2 | 4
3 | 5
4 | 1
5 | 3
if you have the randomly sorted number for your incremented number, it is easy to create a hash from that. Just think about your possible chars as numbers. You get it righgt?
Assuming you have a good algorithm for random numbers, you can make a pretty good hash table. However, there also is a way to find an algorithm, providing you with the numbers as they increase. So in this example it would give you col2 = fn(col1) so i.e. 4 = fn(2).
All you have to do is take the result and re-enginer it into a formular :D
Otherwise you have to fill the table initially.
To give you a glimpse insight into the math of it, think of a function that uses odd/even characteristics of the number and combines it with addition.
With n digits using a range of 62 possibilitys (case sensitive letters and numbers) per char you have 62^n possibilities.
For 4 digits that makes 14776336 possibilities (62^4).
Thou that might sound just wonderfull, you can imagine that having a table, prefilled with 14776336 id's is not the cleanest solution.
Still, i hope this at least leads into the right direction.
EDIT:
We started a discussion on math.stackexchange.com. IT has some additional information on how to create a function for our needs.
You can use something like following
<?php
// chars
$chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789!##$%^&*()-+';
// convert to array
$arr = str_split($chars, 1);
// shuffle the array
shuffle($arr);
// array to chars with 8 chars
echo substr(implode('', $arr), 0, 8);
?>
You can use this function :
// RETRUN 24 digit of UNIX ID :
public function getComplexIDTicket(){ // duplicate method on Rest.php
$arrAZ1 = range('A','Z');
$arrAZ2 = range('A','Z');
$arrAZ3 = range('A','Z');
$arrs1 = range('A','Z');
$arrs2 = range('A','Z');
$arrs3 = range('A','Z');
$a1 = $arrAZ1[rand(0,25)];
$a2 = $arrAZ2[rand(0,25)];
$a3 = $arrAZ3[rand(0,25)];
$s1 = $arrs1[rand(0,25)];
$s2 = $arrs2[rand(0,25)];
$s3 = $arrs3[rand(0,25)];
$s = $s1.$s2.$s3;
$t = microtime(true);
$micro = sprintf("%07d",($t - floor($t)) * 10000000);
$id = date('ymdHis').strtoupper(dechex(substr($micro,0,7)));
$id = str_pad($id, 24, $a3.$a2.$a1.$s, STR_PAD_RIGHT);
// 151106214010 3DDBF0 L D C SM4
return $id;
}
I want to generate unique identificator in following 12 numeric format:
YYYYMMDDXXXX
Example:
201403052318
Where:
YYYYMMDD is a current date value and other XXXX is randomly generated value.
$today = date("Ymd");
$rand = sprintf("%04d", rand(0,9999));
$unique = $today . $rand;
Daily required unique volume is about 100. What methods using PHP should I use to prevent possible duplicates in rand values or make all id maximum unique? Maybe possible use current time functions to compact these numbers in last 4 characters?
EDITED:
Unique value connected to MySQL database as prime index of table. It is initial values not connected to any stored information in database.
You can't rely on rand() , There is a possibility you will generate a duplicate (Pretty rare for a rand(0,9999) to generate a duplicate, but that will at some point).
So instead of going for rand(), just create an incremental value (say.. starting from 1) and append to your generated date.
Next time when you regenerate a new id, grab that incremental value's (say if you had stored it somewhere.. must be 1 right ?) status, increment it and append it to your new date.
Not an ideal solution.. (Critics welcome)
You can make use of a uniqid coupled with sha-1 and time and do a substr() on them for first 4 chars.
<?php
$today = date("Ymd");
$rand = strtoupper(substr(uniqid(sha1(time())),0,4));
echo $unique = $today . $rand;
OUTPUT :
201403094B3F
I needed to do something similar, a solution that would keep time and also keep the id unique and i ended up with a solution to use PHP function time() like this
$reference_number = 'BFF-' . time(); you can change the BFF to something that makes more sense to your business logic.
My unique reference id looks like BFF-1393327176 and the number can be converted from Unix to real time which will give you, Tue, 25 Feb 2014 11:19:36
I hope this helps
If the unique values generated once, you just need to make conditional choice for the rand value and store the value in an array which is going to be the condition -using inarray-:
$amount = 100; // the amount of ids
$previousValues = array();
for ($i = 0; $i < $amount; $i++){
$rand = rand(0,9999);
while (in_array($rand, $previousValues)){
$rand = rand(0, 9999);
}
$previousValues[] = $rand;
$today = date("Ymd");
$unique = $today.$rand;
echo $unique."\n";
}
Checkout this demo.
A possible solution for creating unique "Unique Order Number" is following, I assume that you have orders table and field order_number, then the code is:
$orderNumber = DB::table('orders')->max('order_number') + random_int(10, 100);
If first order number is inserted as "100000000000" that method will give you this numbers:
100000000025
100000000056
100000000089
100000000123
100000000199
100000000232
100000000249
with that approach there is no possibility for non-unique number, but cons is that each number is greater the previous (not 100% random) but that approach is acceptable for most of the cases.
General Overview:
The function below spits out a random ID. I'm using this to provide a confirmation alias to identify a record. However, I've had to check for collision(however unlikely), because we are only using a five digit length. With the allowed characters listed below, it comes out to about 33 million plus combinations. Eventually we will get to five million or so records so collision becomes an issue.
The Problem:
Checking for dupe aliases is inefficient and resource heavy. Five million records is a lot to search through. Especially when this search is being conducted concurrently by different users.
My Question:
Is there a way to 'auto increment' the combinations allowed by this function? Meaning I only have to search for the last record's alias and move on to the next combination?
Acknowledged Limitations:
I realize the code would be vastly different than the function below. I also realize that mysql has an auto increment feature for numerical IDs, but the project is requiring a five digit alias with the allowed characters of '23456789ABCDEFGHJKLMNPQRSTUVWXYZ'. My hands are tied on that issue.
My Current Function:
public function random_id_gen($length)
{
$characters = '23456789ABCDEFGHJKLMNPQRSTUVWXYZ';
$max = strlen($characters) - 1;
$string = '';
for ($i = 0; $i < $length; $i++) {
$string .= $characters[mt_rand(0, $max)];
}
return $string;
}
Why not just create a unique index on the alias column?
CREATE UNIQUE INDEX uniq_alias ON MyTable(alias);
at which point you can try your insert/update and if it returns an error, generate a new alias and try again.
What you really need to do is convert from base 10 to base strlen($characters).
PHP comes with a built in base_convert function, but it doesn't do exactly what you want as it will use the numbers zero, one and the letter 'o', which you don't have in your version. So you'll need a function to map the values from base_convert from/to your values:
function map_basing($number, $from_characters, $to_characters) {
if ( strlen($from_characters) != strlen($to_characters)) {
// ERROR!
}
$mapped = '';
foreach( $ch in $number ) {
$pos = strpos($from_characters, $ch);
if ( $pos !== false ) {
$mapped .= $to_characters[$pos];
} else {
// ERROR!
}
}
return $mapped;
}
Now that you have that:
public function next_id($last_id)
{
$my_characters = '23456789ABCDEFGHJKLMNPQRSTUVWXYZ';
$std_characters ='0123456789abcdefghijklmnopqrstuv';
// Map from your basing to the standard basing.
$mapped = map_basing($last_id, $my_characters, $std_characters);
// Convert to base 10 integer and increment.
$intval = base_convert($mapped, strlen($my_characters), 10);
$intval++;
// Convert to standard basing, then to our custom basing.
$newval_std = base_convert($intval, 10, strlen($my_characters));
$newval = map_basing($newval_std, $std_characters, $my_characters);
return $newval;
}
Might be some syntax errors in there, but you should get the gist of it.
You could roll your own auto-increment. It would probably be fairly inefficient though as you'd have to figure out where in the process your increment was. For instance, if you assigned the position in your random string as an integer and started with (0)(0)(0)(0)(0) that would equate to 22222 as the ID. Then to get the next one, just increment the last value to (0)(0)(0)(0)(1) which would translate into 22223. If the last one gets to your string length, then make it 0 and increment the second to last, etc... It's not exactly random, but it would be incremented and unique.
What I am trying to do is create a 12 character id for articles on my website similar to how youtube handles their video id (http://www.youtube.com/watch?v=53iddd5IcSU). Right now I am generating an MD5 hash and then grabbing 12 characters of it like this:
$ArticleId = substr(MD5("Article".$currentID),10,12)
where $currentID is the numeric ID from the database (eg 144)
I am slightly paranoid that I will run into a duplicate $ArticleId, but realistically what are the chances that this will happen? And also, being that the column in my database is unique, how can I handle this rare scenario without having an ugly error thrown?
P.S. I made a small script to check for duplicates within the first 5000 $ArticleId's and there were none.
EDIT: I don't like the way the base64_encode hashes look so I did this:
function retryAID($currentID)
{
$AID = substr(MD5("Article".$currentID*2),10,12);
$setAID = "UPDATE `table` SET `artID` = '$AID' WHERE `id` = $currentID ";
mysql_query($setLID) or retryAID($currentID);
}
$AID = substr(MD5("Article".$currentID),10,12);
$setAID = "UPDATE `table` SET `artID` = '$AID' WHERE `id` = $currentID ";
mysql_query($setAID) or retryAID($currentID);
Since the AID column is unique the mysql_query will throw an error and the retryAID function will find a unique id...
What's wrong with using a sequential id? The database will handle this for you.
That aside, 12 characters is still 96 bits. 296 = 79228162514264337593543950336 possible hashes. Even though MD5 is known to have collision vulnerabilities, there's a world of difference between the possibility of a collision and the probability of actually seeing one.
Update:
Based on the return value of the PHP md5 function you're using, my numbers above aren't quite right.
Returns the hash as a 32-character hexadecimal number.
Since you're taking 12 characters from a 32-character hexadecimal number (and not 12 bytes of the 128-bit hash), the actual number of possible hashes you could end up with is 1612 = 281474976710656. Still quite a few.
<?php
function get_id()
{
$max = 1679615; // pow(36, 4) - 1;
$id = '';
for ($i = 0; $i < 3; ++$i)
{
$r = mt_rand(0, $max);
$id .= str_pad(base_convert($r, 10, 36), 4, "0", STR_PAD_LEFT);
}
return $id;
}
?>
Returns a 12 character number in base-36, which gives 4,738,381,338,321,616,896 possibilities. (The probability of collision depends on the distribution of the random number generator.)
To ensure no collisions, you'll need to loop:
<?php
do {
$id = get_id();
} while ( !update_id($id) );
?>
No not very unique.
Why not base64 encode it if you need it shorter?
How about UUID ?
http://php.net/manual/en/function.uniqid.php