sqlite_udf_encode_binary

(PHP 5 < 5.4.0, PECL sqlite >= 1.0.0)

sqlite_udf_encode_binary — Encode binary data before returning it from an UDF

说明

string sqlite_udf_encode_binary ( string $data )

sqlite_udf_encode_binary() applies a binary encoding to the data so that it can be safely returned from queries (since the underlying libsqlite API is not binary safe).

If there is a chance that your data might be binary unsafe (e.g.: it contains a NUL byte in the middle rather than at the end, or if it has and 0x01 byte as the first character) then you must call this function to encode the return value from your UDF.

PHP does not perform this encode/decode operation automatically as it would severely impact performance if it did.

Note:
Do not use sqlite_escape_string() to quote strings returned from UDF's as it will lead to double-quoting of the data. Use sqlite_udf_encode_binary() instead!

参数

data: The string being encoded.

返回值

The encoded string.

参见

sqlite_udf_decode_binary() - Decode binary data passed as parameters to an UDF
sqlite_escape_string() - Escapes a string for use as a query parameter
sqlite_create_function() - Registers a "regular" User Defined Function for use in SQL statements
sqlite_create_aggregate() - Register an aggregating UDF for use in SQL statements

User Contributed Notes

B. Keil 07-May-2013 06:57


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