如何rowCount一个空数据

Question

I want user to have valid email thats why i check if the comform there email.

I get the username and count the rows who have that username and Activation set to NULL,but if i echo the rowCount = 0 but there is a such a row

$checkMail = $dbh->prepare("SELECT UserID FROM users WHERE username =:username 
AND Activation=''");
$checkMail->bindParam(':username', $_POST['username']);
$checkMail->execute();
echo $exist = $checkMail->rowCount();

Answer 1

If Activation is really NULL, your query should be:

SELECT UserID FROM users WHERE username =:username AND Activation IS NULL