username should be unique if present in database then return error [duplicate]

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
– NoobEditor, Commented Mar 21, 2014 at 7:19
Read about SQL Injection also... - stackoverflow.com/questions/60174/… — Petro Popelyshko
– Petro Popelyshko, Commented Mar 21, 2014 at 7:19

m-farhan · Accepted Answer · 2014-03-21 07:29:40Z

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, 2014 at 7:29

answered Mar 21, 2014 at 7:23

m-farhan

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4 Comments

NoobEditor Over a year ago

logically this answer is correct...but your solution is immensely prone to sql injection ...be aware!! :)

m-farhan Over a year ago

i m 100% agree but i was just answering owner has to apply sanitation on string

m-farhan Over a year ago

@NoobEditor injuction part solved some how

NoobEditor Over a year ago

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!! :)

user2706194 · Accepted Answer · 2014-03-21 07:29:40Z

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, 2014 at 7:29

user2706194

1998 bronze badges

2 Comments

NoobEditor Over a year ago

and how is this "faster"???

user2706194 Over a year ago

its mil-second difference for select * and select column name to whether match or not match.

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