username should be unique if present in database then return error

Question

I am working on a project and I want to check the log in credential according to user. When a new user comes and it is log in, then if username present in database then produce an error !

username exist

Code:

include('connect.php'); 

    $query = mysql_query("SELECT * FROM users WHERE user_name = '". $user_name ."' "); 

    if (mysql_num_rows($query) > 0) 
    { 
     echo 'Username already in use please try another.'; 
    }
    else{
    $opt=$obj->addStudent($user_name,$user_pass,$user_email,$user_contact);
    }
}

I want to check ignore case sensitive also.

ok...i read what u wrote...now... **whats your question** ??? — NoobEditor, Mar 21 '14 at 07:19
Read about SQL Injection also... - http://stackoverflow.com/questions/60174/how-can-i-prevent-sql-injection-in-php — Petro Popelyshko, Mar 21 '14 at 07:19
http://stackoverflow.com/questions/5629111/how-can-i-make-sql-case-sensitive-string-comparison-on-mysql this might help — mesutozer, Mar 21 '14 at 07:20

m-farhan · Answer 1 · 2014-03-21T07:29:40.847

1

include('connect.php'); 

    $query = mysql_query("SELECT * FROM users WHERE UPPER(user_name) = '". mysql_real_escape_string(strtoupper($user_name)) ."' "); 

    if (mysql_num_rows($query) > 0) 
    { 
     echo 'Username already in use please try another.'; 
    }
    else{
    $opt=$obj->addStudent($user_name,$user_pass,$user_email,$user_contact);
    }
}

this way username :XyZ will be same as xyz

edited Mar 21 '14 at 07:29

answered Mar 21 '14 at 07:23

m-farhan

1,436
13
14

1

logically this answer is correct...but your solution is immensely prone to `sql injection` ...be aware!! :) – NoobEditor Mar 21 '14 at 07:25
i m 100% agree but i was just answering owner has to apply sanitation on string – m-farhan Mar 21 '14 at 07:27
@NoobEditor injuction part solved some how – m-farhan Mar 21 '14 at 07:30
OP will have to decide on what kind of security is needed in the code.... `mysql_` is still insecure but yes does the job of answering OP's question!! :) – NoobEditor Mar 21 '14 at 08:03

score 0 · Answer 2 · answered Mar 21 '14 at 07:29

0

use the faster code for you unique name test.

include('connect.php'); 

    $query = mysql_query("SELECT `user_name` FROM users WHERE LOWER(user_name) = LOWER(". $user_name .")"); 

    if (mysql_num_rows($query) > 0) 
    { 
     echo 'Username already in use please try another.'; 
    }
    else{
    $opt=$obj->addStudent($user_name,$user_pass,$user_email,$user_contact);
    }

answered Mar 21 '14 at 07:29

user2706194

199
8

and how is this "faster"??? – NoobEditor Mar 21 '14 at 08:01
its mil-second difference for select * and select column name to whether match or not match. – user2706194 Mar 21 '14 at 09:56

username should be unique if present in database then return error

2 Answers2