PHP不区分大小写吗？

Question

I am using MySQL and PHP . In my database I have this table called users , and inside the users table have a record:

username: admin

password: password

In my login page, I tried login as (password: password):

• username : ADMIN -> result : can login
• username : admin -> result : can login

I store the username in my database as "admin", all lowercase.

In my PHP authentication page, I didn't include the strtolower() function. Does it mean, in PHP the username form field that I submitted is not case sensitive?

Answer 1

It's not PHP. It's your database query that is not case sensitive.

You can either make one of the operands binary string. For example:

SELECT 'abc' LIKE 'ABC';

This will return 1 or true . While

SELECT 'abc' LIKE BINARY 'ABC';

will return 0 or false .

Answer 2

Yup, as Randell said, it's the database that is case-sensitive. Check this article, for Can we make MySQL to be case sensitive for SELECT queries and can we force a column in MySQL to be always lowercase? .

Answer 3

I think have some way to go before it's clear...

MySQL is NOT case sensitive for queries. SELECT and select mean the same thing.

The data in the tables is stored as is, but since you can only get information out with queries, you need to phrase them carefully.

As Randell said

select 'abc' like 'ABC'

Will return TRUE (so will SELECT 'abc' like 'ABC' ) because LIKE ignores case differences

select 'abc' like binary 'ABC'

will return FALSE (and so will SELECT 'abc' LIKE BINARY 'ABC' ) because LIKE BINARY looks more carefully. There IS a difference at the binary level.

Answer 4

How should it know it's the username form field?

If I remember right, in *nix a username was case-insensitive. Are you using a library to store the userinformation and to compare it?

Answer 5

当您登录时，我认为您应该编写查询来验证用户名和密码在您保存的表中是相同的。