How do I fetch mulitiple rows using fetch(PDO::FETCH_ASSOC) with pdo?

问题

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!

回答1:

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.

回答2:

Fetch does indeed pull the data from the database one at a time, but you need to iterate through the rows until you have all the data.

You might want to pop this into a loop to get all the data:

$stmtAA->fetch(PDO::FETCH_ASSOC);

Something like this should do the trick:

while($row=$this->prepared->fetch(PDO::FETCH_ASSOC))
{
    $this->ID=$row['id'];
    $something=$row['something'];
}

Depending on if you are populating variables or have the code within an object.

来源：https://stackoverflow.com/questions/12105947/how-do-i-fetch-mulitiple-rows-using-fetchpdofetch-assoc-with-pdo

标签

php

pdo

fetch

loops