MySQL select a column with replaced text where it equals a value

Question

I was recently alerted to the fact that gmail email addresses are the same whether you put a "." before "@gmail.com". So "myemail@gmail.com" and "my.email@gmail.com" both send to the "myemail@gmail.com".

As a result, when users sign up on my website, I want to check that they aren't using this exploit to make multiple accounts with essentially the same email address.

I sanitize the email address they send me, log into my database with PDO and then try running this code:

$data=$db->query("SELECT REPLACE(email,'.','') AS email_without_periods FROM account_data HAVING email_without_periods LIKE '".str_replace($sanitizedEmail,".","")."'");

if($row=$data->fetch()){
//It found a match between the sanitized email without decimals and the email rows without decimals. Hey, this dude's trying to create multiple accounts!
    $error="You're trying the email decimal trick! You sneaky devil... ";
}

However, this input doesn't work: it doesn't seem to register any rows.

When I replaced LIKE '".str_replace($sanitizedEmail,".","")."'" with LIKE '%".str_replace($sanitizedEmail,".","")."%'" , it brought back all of the rows.

I basically want to search for str_replace($postEmail,".","") in the database, but to remove all the periods in email rows first. I'm using PDO.

How can I do this?

Answer 1

You have the arguments in the wrong order in str_replace . It should be:

str_replace('.', '', $sanitizedEmail)

You were using the same argument order as SQL's REPLACE function, but they're different.