PHP Case-Write verification

I have a login registration function, when I registered success AA this user, with AA username and AA password input, incredibly also successfully entered, I estimate is the size of the problem, look pointing

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I have a login registration function, when I registered success AA this user, with AA username and AA password input, incredibly also successfully entered, I estimate is the size of the problem, look pointing

What is your database character set? You can choose to take a look with bin.

It is best to unify uppercase or lowercase, the database has no special settings and is case insensitive

The user name is usually converted to lowercase and stored, the user name should not be case-sensitive,
Your situation should be to take a username and password to the database to check. Returning a record is considered successful.
It is more reasonable to use only the user name to check, return the results, use if for password comparison

Most databases are case-insensitive by default, and if you want to differentiate, you have to get rid of the default settings for the database.

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