Should you allow username to use Apostrophe (aka quotes )

Hi,

For websites I've always restricted username to use Apostrophe ' and " and some times even space . If a website necessitate special character then I prefer to create an additional DB field ~DisplayName.

It's easier to forbid the use of Apostrophe, otherwise you will have to escape also your search query to match what has been recorded in the DB.

On the topic I've this https://security.stackexchange.com/questions/202902/is-single-quote-filtering-nonsense

But if you have better documentation feel free to share :)

Thanks