如何使用PHP检索/下载存储在MySQL数据库中的BLOB中的文件

Question

The other day I recently wrote a program that takes a file that a user provided and inserts the actual file(driver) into a MySQL database BLOB. I did the insertion as follows:

$sql = "INSERT INTO Drivers (driver, filename, status, version, environments) VALUES(LOAD_FILE('$driver'), '$filename', $statusid, $driver_version, '$environments')";

As you can see above, the 'driver' field is the BLOB. I have the filename as well in a different field. So the question is, how can I easily get the BLOB and put it back into an actual file? I need to get this into a file so that I can upload it to a server via SCP. I've seen a few examples out there with content headers and such and they all look too complicated. It was easy to load with LOAD_FILE() and I didn't know if there was another simple option to get it back to an actual file? Sorry I don't have any code examples. I really don't know where to start.

Answer 1

Your sql table should have at least two extra fields:

`mime_type` varchar(255) NOT NULL,
`size` int(10) unsigned NOT NULL,

where:

• mime_type is mime_content_type($path) and
• size is the file's size in bytes, filesize($path)

and PHP code should look like:

header("Pragma: public");
header("Expires: 0");
header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
header("Content-Type: {$file['mime_type']}");
header("Content-Transfer-Encoding: binary");
header("Content-Length: {$file['size']}");
header("Content-disposition: inline; filename= {$file['filename']}");

return $file['driver'];

The reasons for storing data as binary in SQL are dictated by business rules. For example, I store contracts that have to remain private.