关闭函数内部的PDO连接

Question

In this PHP documentation it gives the following example of how to close a connection:

$dbh = new PDO('mysql:host=localhost;dbname=test', $user, $pass);
// use the connection here


// and now we're done; close it
$dbh = null;

But what if I'm using it in a function where $dbh has only local scope, do I have to set it to null, or will the connection close when the function returns?

In my below example, is the connection closed?

public function doDBWork(){
    $dbh = new PDO('mysql:host=localhost;dbname=test', $user, $pass);
    // use the connection here

    return true;
}

Answer 1

Per the documentation:

you [close the connection] by assigning NULL to the variable that holds the object. If you don't do this explicitly, PHP will automatically close the connection when your script ends.

So the connection will not be closed at the end of the function since you did not assign null. Although it is inaccessible since its scope is local to the function, it technically won't be closed until the end of the script.

Note: In general, I don't recommend establishing and closing database connections within function calls.