note 112117 deleted from function.sqlite-udf-encode-binary by cmb
| From: | cmb@php.net | Date: | Mon, 02 Nov 2020 15:04:04 +0000 |
| Subject: | note 112117 deleted from function.sqlite-udf-encode-binary by cmb | ||
| References: | 1 | Groups: | php.notes |
| Request: | Send a blank email to php-notes+get-215762@lists.php.net to get a copy of this message | ||
Note Submitter: B. Keil
----
I wrote a script to transfer my old data from a mysql database, performing some changes to a sqlite3
database. When I realized that that the sqlite interfaces is no longer included in PHP and my PECL
didn't get it installed it was too late.
However, there is a very easy, though not particularly performant way to get the job done like in
the "sqlite_encode_blob" function I present below. Note that this does ONLY encode the
data. To actually use it in a query you will have to wrap it like: X'data' See the example
below.
#!/usr/bin/php
<?php
function sqlite_encode_blob($data) {
$result = "";
for ($i = 0; $i < strlen($data); $i++) {
$result .= sprintf("%02X", ord(substr($data, $i, 1)));
}
return $result;
}
error_reporting(E_ALL);
$original = "62.jpg";
$data = file_get_contents($original);
$before = microtime(true);
$encodedData = sqlite_encode_blob($data);
$after = microtime(true);
unset($data);
echo "Encoding time needed: ".($after - $before)." seconds.\n";
$sql = <<<QUERY
BEGIN;
CREATE TABLE test(test BLOB);
INSERT INTO test(test) VALUES ( X'$encodedData' );
COMMIT;
QUERY;
unset($encodedData);
file_put_contents("test.sql", $sql);
sqlite3 blob_test.db < test.sql
?>
The tricky part is to get the data back out of the database - that is not possible with the command
line tool as far as I can tell. You will have to use a language with an actual API.
The following example is written in C and compiles on a linux box where the sqlite3 API is installed
using:
gcc -o test test.c pkg-config --cflags --libs sqlite3
Note that this has absolutely no error checking whatsoever. If the slightest thing goes wrong it
will likely cause a segmentation fault and likely leave the database corrupted.
# FILE test.c START
#include <stdlib.h>
#include <stdio.h>
#include <sqlite3.h>
#define DB_FILE "blob_test.db"
#define QUERY_STRING "SELECT data FROM test"
#define STORAGE_FILE "test.jpg"
int main(int argc, char** argv) {
sqlite3 *db = NULL;
int size = 0;
const char *data = NULL;
sqlite3_stmt *query = NULL;
const char *rest = NULL;
FILE *file = NULL;
sqlite3_open(DB_FILE, &db);
sqlite3_prepare_v2(db, QUERY_STRING, sizeof(QUERY_STRING), &query, &rest);
sqlite3_step(query);
size = sqlite3_column_bytes(query, 0);
data = sqlite3_column_blob(query, 0);
file = fopen(STORAGE_FILE, "w");
fwrite(data, 1, size, file);
fclose(file);
sqlite3_finalize(query);
sqlite3_close(db);
return 0;
}
# FILE test.c END