PHP & PDO: Which is faster? Fetching COUNT(*) or rowCount()?

Question

OK, my problem is that I have a script that loads on every page, it checks if a signed in user is banned or not by checking a column named "banned" that can output either 0 (not banned) or 1 (banned). I've tried searching for this, but didn't find an absolute answer to which performs better:

Fetching a COUNT(*) query:

$query = $PDO->prepare("SELECT COUNT(*) FROM users WHERE id = :ID AND banned = 1");
$query->execute(array(":ID" => $USER_ID));
if ($query->fetchColumn() > 0) {
    // USER IS BANNED! SHOW ERROR MESSAGE!
}

Using rowCount() instead of fetching:

$query = $PDO->prepare("SELECT banned FROM users WHERE id = :ID AND banned = 1");
$query->execute(array(":ID" => $USER_ID));
if ($query->rowCount() > 0) {
    // USER IS BANNED! SHOW ERROR MESSAGE!
}

Answer 1

I performed a benchmark with 200k randomly generated entries with three columns id, name, and banned. 3467 users were randomly selected to be banned. I am using the following configuration on an AWS micro instance:

PHP 7.0.30-0

Ubuntu 0.16.04.1

MySQL 5.7.22-0

Benchmark results:

COUNT(*) execution took 0.00022506713867188 seconds

rowcount() execution took 0.00011420249938965 seconds

rowcount() is the winner.

Answer 2

1. select COUNT(*) is different from select *.

2. fetchColumn() and rowCount() both are excuted by mysql

   (1) if data is too much in mysql, it will effect performs

   (2) another , you can think they are same and you can use both of them

3. if you choose the first method, mysql will return you all of the data result, it will use data transform, net, time, etc

so you should consider about your real enviroment to decide use which one.