How to write an HTML Pattern attribute?

Question

I want an HTML Pattern attribute in order to have only letters A-Z, a-z, 0-9, and spaces.

I have the following which work, but the only problem is that, it also accepts it if I just enter a space and click submit.

[A-Za-z 0-9]+

For that reason I decided I am going to require atleast 3 characters, one of them being a letter. That lead me to write this:

[A-Za-z 0-9](?=.*[A-Za-z]).{3,}

But on this one, if I enter Jui;18 it accepts it. an since this is going to based into sql, that will create problems. Why does it accept the semicolon and what is the right pattern I need?

"based into sql"? What kind of problems? Not SQL injection, I hope; you should be using parameterized queries. Client-side validation like the pattern attribute wouldn’t help anyway. — Ry-
– Ry- ♦, Commented Dec 29, 2017 at 7:13
@Ryan It is SQL injection because I have a PHP file that creates a database in the name entered in the text field. What do you recommend for me to solve the problem, then? — Rixwaan
– Rixwaan, Commented Dec 29, 2017 at 7:15
Why are you creating databases dynamically? But you would at least validate it on the server side with the same pattern. Test that this part is safe without the pattern attribute on the client, then add it. — Ry-
– Ry- ♦, Commented Dec 29, 2017 at 7:17
@AndyG I am removing the Space in php side, but adding with slace into a table — Rixwaan
– Rixwaan, Commented Dec 29, 2017 at 17:45

Ry- · Accepted Answer · 2017-12-29 07:16:30Z

1

Start with your pattern:

[A-Za-z 0-9]+

Require at least 3 characters:

[A-Za-z 0-9]{3,}

Require a letter:

(?=.*[A-Za-z])[A-Za-z 0-9]{3,}

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