Change meta description/keywords dynamically with php

Question

Im trying to grab some info from the db and use it as meta desc and keyword. But something isnt working as it supposed to.

EDIT: after alot of help i got it semi working. If there is no blogID i want it to fallback on the other part... that part of the script aint working, any ideas?

<?php
$dsn = "sqlsrv:Server=localhost;Database=blog";
$conn = new PDO($dsn, "**********", "********");
$conn->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );
$id = $_GET['postID'];
$sql = "SELECT * FROM blog_posts WHERE blogID=:id ORDER BY blogID DESC";
 $stmt = $conn->prepare($sql);
                    $stmt->execute (array($id));
                    while($metta = $stmt->fetch(PDO::FETCH_BOTH) )

if (isset($metta['blogID']) && !empty($metta['blogID'])) { 
$keywords = $metta['keywords']; 
$description = $metta['description']; 
} else { 
$keywords = "blalbalbalblabla"; 
$description = "blabla"; 
}

?>

Answer 1

It might not be the prettiest code... but it works!

<?php
$dsn = "sqlsrv:Server=localhost;Database=blog";
$conn = new PDO($dsn, "*****", "*******");
$conn->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );
$id = $_GET['postID'];
$sql = "SELECT * FROM blog_posts WHERE blogID=:id";
 $stmt = $conn->prepare($sql);
                    $stmt->execute (array($id));
                    $metta = $stmt->fetch(PDO::FETCH_BOTH);

if (isset($_GET['postID'])) { 
$keywords = $metta['keywords']; 
$description = $metta['description']; 

}
sqlsrv_close($con);
?>


<meta name="description" content="<?= isset($description) ? $description : 'blablabla'; ?>">
        <meta name="keywords" content="<?= isset($keywords) ? $keywords : 'blablabla'; ?>">