How to check EXISTS result - PDO - php

Question

I use a http://php.net/ page code for conecting with PDO. I Add the EXIST term. How to check if the EXISTS return false? If is not posible, how to check if select return an empty result?
try {
$conn = new PDO("mysql:host=$servername;dbname=xxxx", $username, $password);
// set the PDO error mode to exception
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
echo "Connected successfully";
getUsers($conn,$po[0]);
$conn = null;
}
catch(PDOException $e)
{
echo "Connection failed: " . $e->getMessage();
}
function getUsers($con,$po){
$sql = "SELECT * FROM usuarios WHERE EXISTS (SELECT id FROM webs WHERE name='$po')";
foreach ($con->query($sql) as $row) {
print $row['nombre'] . "\n";
print $row['id'] . "\n";
print $row['email'] . "\n";
}
}

Answer 1

The WHERE EXISTS returns a standard SELECT result (rows) based on the subquery after key EXISTS
So, to check if the EXISTS fails, you have to use rowCount, that return the number of rows returned by the query:
$result = $con->query($sql);
if( $result->rowCount() > 0 ) echo "EXISTS";
else echo "NOT EXISTS";
(Edit:)
Please note:
As noted in the comments below, the rowCount() works fine in this case and always with mySQL database structures, but «this behaviour is not guaranteed for all database» structures: with sqLite, i.e., it doesn't works.

Answer 2

if you will use like this then it will work and no require for check condition
$rows = $con->query($sql);
if($rows){
foreach ($rows as $row) {
print $row['nombre'] . "\n";
print $row['id'] . "\n";
print $row['email'] . "\n";
}
}