How can I make an id like EMP01, EMP02 in phpmyadmin ?

You're working with a database - and every column has a 'type'. An ID is very often an integer, and often this is allowed to be generated automatically by the system to avoid duplication; other times, it may be a number assigned by an administrator of some type.

Integers (or a you say, numbers) are used because they're very efficiently stored and used, and with the rarest of exceptions, take up far less storage than character names. Comparing them is very easy, too.

I suggest you check through your documentation and decide how to enter a user userID of a character type (which holds numbers/letters).

Since you didn't say just which ID you're trying to add or change and how/where you were trying to change it, I can't be more specific. But - by way of the friendliest of warnings:   find and read the manuals before you end up with a no database (corrupted)! PhpMyAdmin is just what it sounds like