Saving hexadecimal data in the database

Question

I need to register in the database a document or image in hexadecimal format and then recover these data by converting them back to correct format.

Answer 1

PHP already has its own functions for this:

string hex2bin ( string $data )

that converts the string hehadecimal passed in parameter $data in a binary format, which can be stored in a BLOB in the database, or convert data from a Varchar to string, if you are storing in hexa but using the data in bytes ...

...and also the

string bin2hex ( string $str )

that converts the string spent in $str and returns the corresponding hexadecimal, so when you recover the data from BLOB, can convert them back to hexa, or if you are using "the other way around", you can take data in bytes and use this function to convert the data to a string hexa, which can be stored in a Varchar.

To use them, it depends on your practical case. The important thing is to know that by taking the data in hexadecimal, you can pass them to binary with hex2bin, effectively decreasing their space by 50% to store in a BLOB in the database, and while recovering DB data, just use the bin2hex to have the data in hexa again.

Examples:

<?php
   $data = '546573746520646520636f6e76657273616f';
   echo hex2bin( $data );
?>

Exit:

Teste de conversao

<?php
   $data = file_get_contents( 'teste.jpg' );
   echo bin2hex( $data );
?>

Exit:

FFD8FFE102DE45786966000049492A00080000000F000001030001000000100A...