一个查询，一张表，两个count（）

Question

I want to check if username and email taken in my registration script.

This is how I check with query:

$emailcheck = "SELECT COUNT(email) AS nume FROM members WHERE email = :email";
//bindValue
//execute
//fetch
if($rowe['nume'] > 0){
$errors[] = "E-mail exist.";
} 

And also I'm doing the same thing for username;

$usercheck = "SELECT COUNT(username) AS numu FROM members WHERE username = :username";
//bindValue
//execute
//fetch
if($rowu['numu'] > 0){
$errors[] = "Username taken.";
} 

*

I want to go one step further and handle all of stuff with one query.

But I couldn't came up with such query.

I tried:

$check = "SELECT COUNT(username) AS numu and COUNT(email) AS nume FROM members WHERE username = :username OR email = :email";

but probably It's ridiculous.

How to handle what I want with one query?

And after I want to check like that:

if($row['numu'] > 0){
$errors[] = "Username taken.";
} 
if($rowe['nume'] > 0){
$errors[] = "E-mail exist.";
} 

So it will be less code, instead of connecting same table twice and bindValue, execute, fetch for second time.

Answer 1

You can just do Union All to unite those queries:

SELECT COUNT(email) AS num FROM members WHERE email = :email
UNION ALL
SELECT COUNT(username) AS num FROM members WHERE username = :username

Then extract 2 according rows.

OR, MySQL allows this thing:

SELECT 
    (SELECT COUNT(email) FROM members WHERE email = :email) as nume,
    (SELECT COUNT(username) FROM members WHERE username = :username) as numu

if you want 1 rows with 2 columns.

Do that only if you need to see which one is already present. Otherwise just do this:

SELECT 1 FROM members WHERE email = :email OR username = :username LIMIT 1

Yes, consider not doing count() because you don't need to count all the rows. You just need to stop if you find just one. So either do a LIMIT or IF EXISTS()

Answer 2

I don't think you really need to count. Assuming you want to check if either username or email already exist because they are required to be unique on your user table, you can do this:

First, add a unique index to each of those columns in your database. You may already have this, but if you want those values to be unique, this will ensure that even if your PHP code fails to do so for some reason.

Then you can use this query:

SELECT username, email FROM members WHERE username = :username OR email = :email

This will return either zero, one, or two rows, where:

• 0 = neither username nor email was found
• 1 = one row was found having either username, email, or both
• 2 = username was found in one row and email was found in another

Then you can loop over your results, comparing them to the user input, and set your errors.

while ($row = //fetch) {
    if ($row['username'] == $username) {
        $errors[] = "Username taken.";
    } 
    if ($row['email'] == $email) {
        $errors[] = "E-mail exist.";
    } 
}

Answer 3

You can try this after removing and between count

   $check = "SELECT COUNT(username) AS uname , 
       COUNT(email) AS uemail FROM members 
       WHERE (username = :username OR email = :email)";