PHP array to mysql [duplicate] - php

Question

I'm looking for a SQL-injection-secure technique to insert a lot of rows (ca. 2000) at once with PHP and MySQLi.
I have an array with all the values that have to be include.
Currently I'm doing that:
<?php
$array = array("array", "with", "about", "2000", "values");
foreach ($array as $one)
{
$query = "INSERT INTO table (link) VALUES ( ?)";
$stmt = $mysqli->prepare($query);
$stmt ->bind_param("s", $one);
$stmt->execute();
$stmt->close();
}
?>
I tried call_user_func_array(), but it caused a stack overflow.
What is a faster method to do this (like inserting them all at once?), but still secure against SQL injections (like a prepared statement) and stack overflows?

Answer 1

You should be able to greatly increase the speed by putting your inserts inside a transaction. You can also move your prepare and bind statements outside of your loop.
$array = array("array", "with", "about", "2000", "values");
$query = "INSERT INTO table (link) VALUES (?)";
$stmt = $mysqli->prepare($query);
$stmt ->bind_param("s", $one);
$mysqli->query("START TRANSACTION");
foreach ($array as $one) {
$stmt->execute();
}
$stmt->close();
$mysqli->query("COMMIT");
I tested this code with 10,000 iterations on my web server.
Without transaction: 226 seconds.
With transaction: 2 seconds.
Or a two order of magnitude speed increase, at least for that test.

Answer 2

Trying this again, I don't see why your original code won't work with minor modifications:
$query = "INSERT INTO table (link) VALUES (?)";
$stmt = $mysqli->prepare($query);
$stmt->bind_param("s", $one);
foreach ($array as $one) {
$stmt->execute();
}
$stmt->close();

Answer 3

Yes, you can build a single big query manually, with something like:
$query = "";
foreach ($array as $curvalue) {
if ($query)
$query .= ",";
$query .= "('" . $mysqli->real_escape_string($curvalue) . "')";
}
if ($query) {
$query = "INSERT INTO table (link) VALUES " . $query;
$mysqli->query($query);
}

Answer 4

You should first convert your array into a string. Given that it is an array of strings (not a two-dimentional array), you can use the implode function.
Please be aware that each value should be enclosed into parenthesis and properly escaped to ensure a correct INSERT statement and to avoid the risk of an SQL injection. For proper escaping you can use the quote method of the PDOConnection -- assuming you're connecting to MySQL through PDO. To perform this operation on every entry of your array, you can use array_map.
After escaping each value and imploding them into a single string, you need to put them into the INSERT statement. This can be done with sprintf.
Example:
<?php
$connection = new PDO(/*...*/);
$connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$dataToBeSaved = [
'some',
'data',
'with "quotes"',
'and statements\'); DROP DATABASE facebook_main; --'
];
$connection->query(
sprintf(
'INSERT INTO table (link) VALUES %s',
implode(',',
// for each entry of the array
array_map(function($entry) use ($connection) {
// escape it and wrap it in parenthesis
return sprintf('(%s)', $connection->quote($entry));
}, $dataToBeSaved)
)
)
);
Note: depending on the amount of records you're willing to insert into the database, you may want to split them into several INSERT statements.