如何在我的情况下正确使用SQL计数

Question

On my website, I have implemented a reply system, or a "mention" system and now I want to let the user know when they have a new mention without having to go to the mentions page and manually checking. On my website, I have a sidebar with navigation links, I'd like to have the mentions link say something like "Mentions(2)" where 2 is however many new mentions you have.

So the only problem I am having is returning the count of the number of rows that this SQL query returns.

Using this I get "Mentions(Array)", but how would I retrieve the number of how many rows is being selected?

$getMentions = $db->prepare("SELECT COUNT(seen) AS readMentions FROM mentions WHERE mentioned = :username AND seen = 0");

$getMentions->execute(array(':username' => $_SESSION['USER']));

$mentions = $getMentions->fetch();

echo "<li><a href='../mentions.php'>Mentions (".$mentions.")</a></li>";

Answer 1

fetch returns an array indexed, by default, by both column name and a zero based index with the results of the row. So instead of echo ing $mentions , you should be echo ing $mentions['readMentions'] or $mentions[0] .