Database not checking if username is free

Question

Okay, I have another problem, the code is fixed now:

{ 
   //Check if user already exists 
    $un_check = mysql_query("SELECT Username FROM users WHERE Username = '$un'");  
    if(mysql_num_rows($un_check) >0) {
echo "Username already exists";
}
else{
 // Username Free
}

But the database still allows usernames to be the same. Also, even though it says "username already exists" I still creates the account anyway?

any ideas?

Are you sure that the username will always be `'POSTVALUE'`? — Ignacio Vazquez-Abrams, Jun 25 '13 at 13:12
shouldn't your `mysql_num_rows($un)` be `mysql_num_rows($un_check)`?? — Pedro Estrada, Jun 25 '13 at 13:13
Why don't you put a `UNIQUE` constraint on the `Username` column? — Jimbo, Jun 25 '13 at 13:14
Please understand that Stackoverflow is not your personal bugtracker. Instead learn how to debug PHP code. You will do it more than once in your life. — hakre, Jun 25 '13 at 13:15
@IgnacioVazquez-Abrams Well, I know it'll be $un but I tried that as well and It still doesn't work. — user2517092, Jun 25 '13 at 13:17

score 2 · Answer 1 · edited May 25 '19 at 14:21

2

Seems typo change $un to $un_check,

if(mysql_num_rows($un_check) >0) {...

Always have your PHP errors turn on at-least on development environment,

error_reporting(E_ALL);

Note: Please, don't use mysql_* functions in new code. They are no longer maintained and are officially deprecated. See the red box? Learn about prepared statements instead, and use PDO, or MySQLi - this article will help you decide which. If you choose PDO, here is a good tutorial.

edited May 25 '19 at 14:21

Zoe

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answered Jun 25 '13 at 13:13

Rikesh

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zero tolerance on typo questions and answers. you don't even point out how to enable error messages. – hakre Jun 25 '13 at 13:14
Glad to help you. Don't forget to check my notes though :) – Rikesh Jun 25 '13 at 13:23
the boldness and underlining is on **you**, thumbs up, hope to see you soon again. – hakre Jun 25 '13 at 13:23
@hakre - was that a **sarcasm** ? – Rikesh Jun 25 '13 at 13:26

score 0 · Answer 2 · answered Jun 25 '13 at 13:13

0

Change this :-

if(mysql_num_rows($un) >0)

to

if(mysql_num_rows($un_check) >0)

answered Jun 25 '13 at 13:13

Vivek Sadh

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score 0 · Accepted Answer · edited Jun 25 '13 at 13:16

0

try this

$un_check = mysql_query("SELECT Username FROM users WHERE Username = 'POSTVALUE'");  
if(mysql_num_rows($un_check) >0) {
   echo "Username is taken";
}
else{
 // Username Free
}

edited Jun 25 '13 at 13:16

Fallen

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answered Jun 25 '13 at 13:14

Nisarg

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This fixed my errors! (thanks) but it still doesn't let me know if the username exists. – user2517092 Jun 25 '13 at 13:20
Thanks! It's fixed now. (: This did the trick after I changed postvalue to $un. – user2517092 Jun 25 '13 at 13:22

Database not checking if username is free

3 Answers3

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