PHP MySql error Can't read id from database

Question

I'm following login/register tutorial in php and mysql. As you can see in this video: http://www.youtube.com/watch?v=JUk2e8oqOvI&list=PLE134D877783367C7

You can find function user_id_from_username on 06:28 minute.

I have exact function:

function user_id_from_username($username){                  
    $username = sanitize($username);
    return mysql_result(mysql_query("SELECT 'user_id' FROM 'users' WHERE 'username' = '$username'"), 0, 'user_id');
}

But this query never returns user_id. I tried to echo result of this query and I don't get anything. Database is ok, all other queries works fine. If I run this query in mysql workbench again it works. I don't know where is the problem. Can you help me.

If your tutorial teaches you to use `mysql_*` function, that may be a hint that the tutorial is a little bit outdated; Use [`mysqli`](http://www.php.net/manual/en/book.mysqli.php), especially [prepared statement and variable binding](http://www.php.net/manual/en/mysqli.quickstart.prepared-statements.php) instead. — Passerby, Jul 26 '13 at 09:15

score 0 · Answer 1 · answered Jul 26 '13 at 09:14

0

use " insteand of '

"SELECT user_id FROM users WHERE username = '".$username."'"

answered Jul 26 '13 at 09:14

Nightmare

251
1
5

if you use ', all string in ' will be handled as pure string,include $ – Nightmare Jul 26 '13 at 09:17
Nightmare why didn't you edit your post? – Mihai Iorga Jul 26 '13 at 09:18

score 0 · Answer 2 · edited Jul 26 '13 at 09:15

0

return mysql_result(mysql_query("SELECT 'user_id' FROM 'users' WHERE 'username' = '".$username."'"), 0, 'user_id');

edited Jul 26 '13 at 09:15

Mihai Iorga

39,330
16
106
107

answered Jul 26 '13 at 09:14

user2622044

185
3
4
14

Paddyd · Answer 3 · 2013-07-26T09:24:59.143

0

You need to pull the data from mysql_result.

function user_id_from_username($username){
    $username = sanitize($username);
    $result = mysql_result(mysql_query("SELECT 'user_id' FROM 'users' WHERE 'username' = '".$username."'"), 0, 'user_id');
    $row = mysql_fetch_assoc($result);
    return $row['user_id'];    
}

edited Jul 26 '13 at 09:24

answered Jul 26 '13 at 09:15

Paddyd

1,870
16
26

How sure are you that this works? :) – Mihai Iorga Jul 26 '13 at 09:16
you have to fetch the query resultset if you want to obtain data from a query result. But that 'result' is missing a $ sign. – KarelG Jul 26 '13 at 09:24
It is indeed, Fixed ;) – Paddyd Jul 26 '13 at 09:25

score 0 · Accepted Answer · answered Jul 26 '13 at 09:20

0

Remove quotes around user_id, users and username.

Quotes are only for string

mysql_query("SELECT user_id FROM users WHERE username = '$username'")

or optimized

mysql_query('SELECT user_id FROM users WHERE username = "' . $username . '";')

answered Jul 26 '13 at 09:20

Macbric

472
4
10

All of those answers worked but I choose this one, because it's simplest. Thank you. – Alen Jul 26 '13 at 13:17

score 0 · Answer 5 · answered Jul 26 '13 at 09:26

0

WHERE 'username' = '".$username."'"   replace this in query and try again

answered Jul 26 '13 at 09:26

Vikas Gautam

997
7
23

PHP MySql error Can't read id from database

5 Answers5