如何使用 fetch(PDO::FETCH_ASSOC) 和 pdo 获取多行?

testQuery() is the method I use to get all rows from table CATEGORIES

public function __construct()
 {
 self::$tdb = Database::getConnection();
 }



 #mock query to pull results from db
 public function testQuery()
  {
       $queryAA = "SELECT cat_name, cat_description, cat_id FROM CATEGORIES";
       $stmtAA = self::$tdb->prepare($queryAA);


       if ($stmtAA->execute() == true)
        {
             print("Execution was successful");
             return $stmtAA->fetch(PDO::FETCH_ASSOC);   
        }
       else
        {
            print("Warning statment did not successfully execute");
        }
     }

I normally use fetchAll() but I was told to use fetch as it doesn't take up as much memory. But I am having trouble retrieving more than one row using fetch() and the code below.

$test = new test();
$results = $test->testQuery();


foreach ($results as $row)
 {
 print_r($row);
 }

It only fetches 1 row. So how do I retrieve and print multiple rows? Using iteration was mentioned before but I'm not sure to implement it. Any help would greatly be appreciated. Thanks!

解决方案

You could simply return the statement object.
Or if you want to encapsulate it (so that it can only be used to fetch the data) use the SPL's IteratorIterator

return new IteratorIterator($stmtAA);

then you can use

foreach( testQuery() as $row) { ... }

in your script.