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On the PDO::Prepare page it states,

"and helps to prevent SQL injection attacks by eliminating the need to manually quote the parameters"

Knowing this, is there a PHP function like mysql_real_escape_string() that takes care of escaping stings for PDO? Or does PDO take care of all escaping for me?


I realize now that I asked the wrong question. My question really was, "What all does PDO take care of for me?" Which I realize now with these answers that it really only removes the need to escape the quotes. But I would still need to do any other PHP sanitize calls on the values that I pass to the execute function. Such as htmlentities(), strip_tags()...etc...



PDO does not escape the variables. The variables and the SQL command are transferred independently over the MySQL connection. And the SQL tokenizer (parser) never looks at the values. Values are just copied verbatim into the database storage without the possibility of ever causing any harm. That's why there is no need to marshall the data with prepared statements.

Note that this is mostly a speed advantage. With mysql_real_escape_string() you first marshall your variables in PHP, then send an inefficient SQL command to the server, which has to costly segregate the actual SQL command from the values again. That's why it's often said that the security advantage is only implicit, not the primary reason for using PDO.

If you concat the SQL command and don't actually use prepared statments (not good!), then yes, there still is an escape function for PDO: $pdo->quote($string)

Saturday, November 5, 2022

However, thanks to this guys. I found out that you need to pass the value by reference with a & before like that :

foreach($Fields as $Name => &$Value){
    $Query->bindParam(':'.$Name, $Value, PDO::PARAM_STR);

This was driving me nuts.

Actual quote from :

Vili 28-May-2010 12:01

This works ($val by reference):

foreach ($params as $key => &$val){
    $sth->bindParam($key, $val);

This will fail ($val by value, because bindParam needs &$variable):

foreach ($params as $key => $val) {
    $sth->bindParam($key, $val);
Monday, December 12, 2022

I can find nothing clear in the manual, but looking at the User Contributed Notes, the use of parameters is intended for actual values only, not table names, field names etc.

Normal string concatenation should (and can) be used.

$tablename = "tablename";
$stmt = $dbh->prepare("CREATE TABLE `$tablename` (id foo, int bar,...)");
Sunday, October 2, 2022

Well, at second glance your question looks more complex to be answered with just one link

How does php pdo's prepared statements prevent sql injection?

How can prepared statements protect from SQL injection attacks?

What are other pros/cons of using PDO?

Most interesting question.
A greatest PDO disadvantage is: it is peddled and propagated a silver bullet, another idol to worship.
While without understanding it will do no good at all, like any other tool.
PDO has some key features like

  • Database abstraction. It's a myth, as it doesn't alter the SQL syntax itself. And you simply can't use mysql autoincremented ids with Postgre. Not to mention the fact that switching database drivers is not among frequent developer's decisions.
  • Placeholders support, implementing native prepared statements or emulating them. Good approach but very limited one. There are lack of necessary placeholder types, like identifier or SET placeholder.
  • a helper method to get all the records into array without writing a loop. Only one. When you need at least 4 to make your work sensible and less boring.

Does using PDO reduce efficiency?

Again, it is not PDO, but prepared statements that reduces efficiency. It depends on the network latency between the db server and your application but you may count it negligible for the most real world cases.

Monday, September 5, 2022

Since this question has been written, mysql introduced a spaceship operator that allows us to use a regular query to match a null value

WHERE fieldName <=> :fieldName;

will match both a null or any not null value.

So just write your query right away and execute it as usual

$stmt = $db->prepare('SELECT field FROM table WHERE fieldName <=> :fieldName;');
$stmt->execute(['fieldName' => null]);
$result = $stmt->fetchAll(); // whatever fetch method is suitable

And with dynamically built queries it's all the same.

Saturday, November 19, 2022
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