Question

From what I know now about PDO statements and my own experiences on localhost and Google – there are some difficulties with using multiple PDO statements in one query. For instance this situation:

$stmt = $db_people->prepare("SELECT * FROM people WHERE online=1");
$stmt->execute();
$results_people = $stmt->fetch(PDO::FETCH_ASSOC);

On this query I can do simple PDO statement like fetch (in example). But when I want to use PDO statement like this:

$rows = $stmt->rowCount();

It is not possible and the statement will not return the right number of rows. When I do it in the other way around and filling one of the column name – rowCount works correctly like this:

$stmt = $db_people->prepare("SELECT name FROM people WHERE online=1");
$stmt->execute();
$rows = $stmt->rowCount();

And adding fetch after that like this:

$results_people = $stmt->fetch(PDO::FETCH_ASSOC);

Will not work corectly in this example. My question is – How to combine two different PDO statements in one single query? Thank you.

Answer 1

The answer probably depends on which operations you’re trying to combine. For instance, if you’re trying to combine PDOStatement::rowCount() with a SELECT SQL operation, then it’s probably worthwhile to take notice of the warnings in the PDOStatement::rowCount() description which says that rowCount() is not 100% reliable for SELECT statements in all databases.

If the problem you’re trying to solve is specifically limited to counting the result rows of a SELECT, then another approach would be to use PDOStatement::fetchAll() and count the rows in the returned array.