Question

The following is a code snippet of my application. Bear in mind that I am very, very new to PDO (as in, started figuring it out today) so I’m a bit confused.

Now, the if statement returns 1, as it should. This is expected. However, what’s unexpected happens after I set $node: after setting it, it appears to be FALSE. What? Just a few lines before, my fetch() attempt returned the expected value, so I have no idea what’s happening.

$sth = $dbh->prepare("
    SELECT *, COUNT(*) AS num_rows
    FROM flow
    INNER JOIN flow_strings
        USING(node_id)
    WHERE
        (
            parent = 0
            OR parent = :user_flow
        )
        AND source = 0
        AND string = :input
    ");
$sth->bindParam(':user_flow', $user->info->flow);
$sth->bindParam(':input', $input_sentence);
$sth->execute();

// If node exists.
if ($sth->fetch()->num_rows > 0)
{
    // Get the information for the node.
    $node = $sth->fetch();

[...] etc

I am guessing that the cursor is moved ahead, and then there’s nothing left to read, so FALSE is returned. Surely there’s a way to work around this, though! When I run $sth->fetch()->num_rows, I’m not trying to change anyything–I’m just trying to read a value. Is there a workaround? Am I doing something weird? I’m so lost, haha.

Thanks! 🙂

---

EDIT:

Notice: Undefined variable: node_count ... on line 56

// Retrieve all child nodes under $parent.
$node_query = $dbh->prepare("
    SELECT *, COUNT(*) AS num_rows
    FROM flow
    WHERE parent = :parent
    ");
$node_query->bindParam(':parent', $parent);
$node_query->execute();

// If child nodes exist.
if ($node_count = $node_query->fetch() && $node_count->num_rows > 0) // Line 56
{

[...] etc

Answer 1

Assign the data array to some variable and use it without further fetches:

if (($row = $sth->fetch()) && $row->num_rows > 0) {
    // work with $row here
}