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php – PDO support for multiple queries (PDO_MYSQL, PDO_MYSQLND)

Posted by: admin February 25, 2020 Leave a comment

Questions:

I do know that PDO does not support multiple queries getting executed in one statement. I’ve been Googleing and found few posts talking about PDO_MYSQL and PDO_MYSQLND.

PDO_MySQL is a more dangerous
application than any other traditional
MySQL applications. Traditional MySQL
allows only a single SQL query. In
PDO_MySQL there is no such limitation,
but you risk to be injected with
multiple queries.

From: Protection against SQL Injection using PDO and Zend Framework (June 2010; by Julian)

It seems like PDO_MYSQL and PDO_MYSQLND do provide support for multiple queries, but I am not able to find more information about them. Were these projects discontinued? Is there any way now to run multiple queries using PDO.

How to&Answers:

As I know, PDO_MYSQLND replaced PDO_MYSQL in PHP 5.3. Confusing part is that name is still PDO_MYSQL. So now ND is default driver for MySQL+PDO.

Overall, to execute multiple queries at once you need:

  • PHP 5.3+
  • mysqlnd
  • Emulated prepared statements. Make sure PDO::ATTR_EMULATE_PREPARES is set to 1 (default). Alternatively you can avoid using prepared statements and use $pdo->exec directly.

Using exec

$db = new PDO("mysql:host=localhost;dbname=test", 'root', '');

// works regardless of statements emulation
$db->setAttribute(PDO::ATTR_EMULATE_PREPARES, 0);

$sql = "
DELETE FROM car; 
INSERT INTO car(name, type) VALUES ('car1', 'coupe'); 
INSERT INTO car(name, type) VALUES ('car2', 'coupe');
";

try {
    $db->exec($sql);
}
catch (PDOException $e)
{
    echo $e->getMessage();
    die();
}

Using statements

$db = new PDO("mysql:host=localhost;dbname=test", 'root', '');

// works not with the following set to 0. You can comment this line as 1 is default
$db->setAttribute(PDO::ATTR_EMULATE_PREPARES, 1);

$sql = "
DELETE FROM car; 
INSERT INTO car(name, type) VALUES ('car1', 'coupe'); 
INSERT INTO car(name, type) VALUES ('car2', 'coupe');
";

try {
    $stmt = $db->prepare($sql);
    $stmt->execute();
}
catch (PDOException $e)
{
    echo $e->getMessage();
    die();
}

A note:

When using emulated prepared statements, make sure you have set proper encoding (that reflects actual data encoding) in DSN (available since 5.3.6). Otherwise there can be a slight possibility for SQL injection if some odd encoding is used.

Answer:

After half a day of fiddling with this, found out that PDO had a bug where…

//This would run as expected:
$pdo->exec("valid-stmt1; valid-stmt2;");

//This would error out, as expected:
$pdo->exec("non-sense; valid-stmt1;");

//Here is the bug:
$pdo->exec("valid-stmt1; non-sense; valid-stmt3;");

It would execute the "valid-stmt1;", stop on "non-sense;" and never throw an error. Will not run the "valid-stmt3;", return true and lie that everything ran good.

I would expect it to error out on the "non-sense;" but it doesn’t.

Here is where I found this info:
Invalid PDO query does not return an error

Here is the bug:
https://bugs.php.net/bug.php?id=61613


So, I tried doing this with mysqli and haven’t really found any solid answer on how it works so I thought I’s just leave it here for those who want to use it..

try{
    // db connection
    $mysqli = new mysqli("host", "user" , "password", "database");
    if($mysqli->connect_errno){
        throw new Exception("Connection Failed: [".$mysqli->connect_errno. "] : ".$mysqli->connect_error );
        exit();
    }

    // read file.
    // This file has multiple sql statements.
    $file_sql = file_get_contents("filename.sql");

    if($file_sql == "null" || empty($file_sql) || strlen($file_sql) <= 0){
        throw new Exception("File is empty. I wont run it..");
    }

    //run the sql file contents through the mysqli's multi_query function.
    // here is where it gets complicated...
    // if the first query has errors, here is where you get it.
    $sqlFileResult = $mysqli->multi_query($file_sql);
    // this returns false only if there are errros on first sql statement, it doesn't care about the rest of the sql statements.

    $sqlCount = 1;
    if( $sqlFileResult == false ){
        throw new Exception("File: '".$fullpath."' , Query#[".$sqlCount."], [".$mysqli->errno."]: '".$mysqli->error."' }");
    }

    // so handle the errors on the subsequent statements like this.
    // while I have more results. This will start from the second sql statement. The first statement errors are thrown above on the $mysqli->multi_query("SQL"); line
    while($mysqli->more_results()){
        $sqlCount++;
        // load the next result set into mysqli's active buffer. if this fails the $mysqli->error, $mysqli->errno will have appropriate error info.
        if($mysqli->next_result() == false){
            throw new Exception("File: '".$fullpath."' , Query#[".$sqlCount."], Error No: [".$mysqli->errno."]: '".$mysqli->error."' }");
        }
    }
}
catch(Exception $e){
    echo $e->getMessage(). " <pre>".$e->getTraceAsString()."</pre>";
}

Answer:

A quick-and-dirty approach:

function exec_sql_from_file($path, PDO $pdo) {
    if (! preg_match_all("/('(\\.|.)*?'|[^;])+/s", file_get_contents($path), $m))
        return;

    foreach ($m[0] as $sql) {
        if (strlen(trim($sql)))
            $pdo->exec($sql);
    }
}

Splits at reasonable SQL statement end points. There is no error checking, no injection protection. Understand your use before using it. Personally, I use it for seeding raw migration files for integration testing.

Answer:

Like thousands of people, I’m looking for this question:
Can run multiple queries simultaneously, and if there was one error, none would run
I went to this page everywhere

But although the friends here gave good answers, these answers were not good for my problem
So I wrote a function that works well and has almost no problem with sql Injection.
It might be helpful for those who are looking for similar questions so I put them here to use

function arrayOfQuerys($arrayQuery)
{
    $mx = true;
    $conn->beginTransaction();
    try {
        foreach ($arrayQuery AS $item) {
            $stmt = $conn->prepare($item["query"]);
            $stmt->execute($item["params"]);
            $result = $stmt->rowCount();
            if($result == 0)
                $mx = false;
         }
         if($mx == true)
             $conn->commit();
         else
             $conn->rollBack();
    } catch (Exception $e) {
        $conn->rollBack();
        echo "Failed: " . $e->getMessage();
    }
    return $mx;
}

for use(example):

 $arrayQuery = Array(
    Array(
        "query" => "UPDATE test SET title = ? WHERE test.id = ?",
        "params" => Array("aa1", 1)
    ),
    Array(
        "query" => "UPDATE test SET title = ? WHERE test.id = ?",
        "params" => Array("bb1", 2)
    )
);
arrayOfQuerys($arrayQuery);

and my connection:

    try {
        $options = array(
            //For updates where newvalue = oldvalue PDOStatement::rowCount()   returns zero. You can use this:
            PDO::MYSQL_ATTR_FOUND_ROWS => true
        );
        $conn = new PDO("mysql:host=$servername;dbname=$database", $username, $password, $options);
        $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    } catch (PDOException $e) {
        echo "Error connecting to SQL Server: " . $e->getMessage();
    }

Note:
This solution helps you to run multiple statement together,
If an incorrect a statement occurs, it does not execute any other statement

Answer:

Tried following code

 $db = new PDO("mysql:host={$dbhost};dbname={$dbname};charset=utf8", $dbuser, $dbpass, array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION));

Then

 try {
 $db->query('SET NAMES gbk');
 $stmt = $db->prepare('SELECT * FROM 2_1_paidused WHERE NumberRenamed = ? LIMIT 1');
 $stmt->execute(array("\xbf\x27 OR 1=1 /*"));
 }
 catch (PDOException $e){
 echo "DataBase Errorz: " .$e->getMessage() .'<br>';
 }
 catch (Exception $e) {
 echo "General Errorz: ".$e->getMessage() .'<br>';
 }

And got

DataBase Errorz: SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '/*' LIMIT 1' at line 1

If added $db->setAttribute(PDO::ATTR_EMULATE_PREPARES, false); after $db = ...

Then got blank page

If instead SELECT tried DELETE, then in both cases got error like

 DataBase Errorz: SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '* FROM 2_1_paidused WHERE NumberRenamed = '¿\' OR 1=1 /*' LIMIT 1' at line 1

So my conclusion that no injection possible…

Answer:

Try this function : mltiple queries and multiple values insertion.

function employmentStatus($Status) {
$pdo = PDO2::getInstance();

$sql_parts = array(); 
for($i=0; $i<count($Status); $i++){
    $sql_parts[] = "(:userID, :val$i)";
}

$requete = $pdo->dbh->prepare("DELETE FROM employment_status WHERE userid = :userID; INSERT INTO employment_status (userid, status) VALUES ".implode(",", $sql_parts));
$requete->bindParam(":userID", $_SESSION['userID'],PDO::PARAM_INT);
for($i=0; $i<count($Status); $i++){
    $requete->bindParam(":val$i", $Status[$i],PDO::PARAM_STR);
}
if ($requete->execute()) {
    return true;
}
return $requete->errorInfo();
}