RandomKeygen is a free mobile-friendly tool that offers randomly generated keys and passwords you can use to secure any application, service or device. KEY RandomKeygen - The Secure Password & Keygen Generator. This is a short guide on how to generate a random token with PHP. These kind of tokens are used for a number of different reasons: To protect against Cross-Site Request Forgery. These are often referred to as CSRF tokens. To help verify a user’s email address. You send the user’s email address a link that contains a “random” token. Generating an MD5 from a unique ID is naive and reduces much of the value of unique IDs, as well as providing significant (attackable) stricture on the MD5 domain. That's a deeply broken thing to do. The correct approach is to use the unique ID on its own; it's already geared for non-collision.
PHP provides the popular md5() hash function out of the box, which returns 32 a hex character string. It’s a great way to generate a fingerprint for any arbitrary length string. But what if you need to generate an integer fingerprint out of a URL?
Challenge
We faced that challenge in RatingWidget when we had to bind our rating widgets to a unique Int64 IDs based on the website’s page it’s being loaded from. Theoretically we could just store the URLs and query the URL column, but URLs can be very long and creating an index for text column with unknown length is very inefficient.
So if you are working on any kind of dynamic widget development that should load different data based on the URL it’s loaded from, this post will save you tonnes of time.
To simplify the problem, let’s divide it into two sub-challenges:
URL Canonization
In our case, we wanted to assign a unique Int64 for a page, not for a URL. For instance,
http://domain.com?x=1&y=2 and http://domain.com?y=2&x=1 are different URLs but in fact both of them will load the exact same page. Therefore, we wanted to assign them an identical Int64 ID. Thus, by canonizing the URLs before mapping them to Int64, we can convert the URLs to uniform representation.
Basically what this code does is reorder the query string parameters by lexicographical order, and slightly tweak the URL encoding based on RFC 3986 URI syntax standard, to compensate for the different browsers + server URL encoding inconsistency.
Notes:
Converting String to unique Int64 ID for MySql BIGINT Indexed Column
After fooling around with various bit conversion functions like
bindec() , decbin() , base_convert() . We have found out that 64 bit integers and PHP are not playing well. None of the mentioned functions consistently supports 64 bit. After digging around on Google, we were lead to a post about 32 bit limitations in PHP which included the suggestion to use GMP, a really cool library for multiple precision integers. Using this library, we managed to create this one line hash function that generates a 64 bit integer out of arbitrary length string.
Post factum, we could have implemented the CRC64 algorithm which generates a string checksum and should perform faster than MD5. Randomly generate bitcoin private key west. But the advantage of the technique we’ve used over CRC is that we’ve created a one-way-hash function, so we can reuse it for various cryptography purposes in the code.
To find out more about GMP, see here.
Grand Finale
Udf to generate surrogate keys. Combining the URL canonization with the String to Int64 mapping, the final solution looks like this:
Php Unique IdCollision and Performance Test of get64BitHash
Platform: Intel i3, Windows 7 64 bit, PHP 5.3
Iterations: 10,000,000 Times generated get64BitHash Elapsed Time: 460 millisecond for every 100,000 generations Collision: Not found Summary
I hope this straightforward solution will save you time on your next project. If you have comments or any additional use-cases where this technique can be applied, please feel free to comment below.
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This PostgreSQL tutorial explains how to create, add, and drop unique constraints in PostgreSQL with syntax and examples.
What is a unique constraint in PostgreSQL?
A unique constraint is a single field or combination of fields that uniquely defines a record. Some of the fields can contain null values as long as the combination of values is unique.
What is the difference between a unique constraint and a primary key?
Create unique Contraint - Using a CREATE TABLE statementGenerate Unique Key In Php Word
The syntax for creating a unique constraint using a CREATE TABLE statement in PostgreSQL is:
Create Unique Key In Php
Example
Let's look at an example of how to create a unique constraint in PostgreSQL using the CREATE TABLE statement.
In this example, we've created a unique constraint on the order_details table called order_unique. It consists of only one field - the order_id field.
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We could also create a unique constraint with more than one field as in the example below:
Create unique contraint - Using an ALTER TABLE statement
Office mac 2008 product key generator. The syntax for creating a unique constraint using an ALTER TABLE statement in PostgreSQL is:
Example
Let's look at an example of how to add a unique constraint to an existing table in PostgreSQL using the ALTER TABLE statement.
In this example, we've created a unique constraint on the existing order_details table called order_unique. It consists of the field called order_id.
Foreign Key
We could also create a unique constraint with more than one field as in the example below:
Drop Unique Constraint
The syntax for dropping a unique constraint in PostgreSQL is:
Example
Let's look at an example of how to remove a unique constraint from a table in PostgreSQL.
In this example, we're dropping a unique constraint on the order_details table called order_unique.
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