One Little Error...

I'm writing a URL shortener... I have this one error that i just can't seem to get rid of. I feel its really obvious but I'm not seeing it.

(I'm a noob ;) ) Here's the Error:

'mysql_result(): supplied argument is not a valid MySQL result resource in <b>/home2/bythewa1/public_html/jbgc/func.inc.php</b> on line <b>23'

And here's my code from that page.

<?php
include("db.inc.php");

function is_min($url)
{

return(preg_match("/jbgc\.me/i", $url)) ? true : false; 

}


function gen_code()
{
$charset = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';    
return substr(str_shuffle($charset), 0, 6);
}



function exists($code) {
$code = mysql_real_escape_string($code);
$code_exists = mysql_query("SELECT COUNT('url_id') FROM 'mini_shortener' WHERE                  'code'= '$code' LIMIT 1");
return (mysql_result($code_exists, 0) == 1) ? true : false;
 }

开发者_JAVA百科

function shorten($url, $code){
$url = mysql_real_escape_string($url);
$code = mysql_real_escape_string($code);
mysql_query("INSERT INTO 'mini_shortener' VALUES('', '$url', '$code')");
return $code;


}



?>

You have errors in your SQL queries -- and should use the mysql_error() function to find out more about those errors ;-)

Still, in your case, you are using the following query :

SELECT COUNT('url_id') 
FROM 'mini_shortener' 
WHERE 'code'= '$code' 
LIMIT 1

you should not use single-quotes arround the fields names -- but backticks : `
Same in your second query, btw.

With MySQL :

• Single-quotes ' are use arround literal-strings,
• and Backticks ` are use arround names.

SELECT COUNT('url_id') FROM 'mini_shortener' WHERE 'code' = ...

You can't select from a string literal. Try using back-ticks instead of single-quotes.

SELECT COUNT(`url_id`) FROM `mini_shortener` WHERE `code` = ...

The cases where you put column names in single-quotes aren't syntax errors, but they probably don't do what you intend. For instance, 'code' = '$code' will be true only when $code is literally the string 'code'. It does not compare $code to the contents of the column code.

Likewise you need to use back-ticks for the table name in your INSERT statement:

INSERT INTO `mini_shortener` VALUES('', '$url', '$code')

For review:

• MySQL Reference Manual 8.1.1. Strings

A string is a sequence of bytes or characters, enclosed within either single quote (“'”) or double quote (“"”) characters. If the ANSI_QUOTES SQL mode is enabled, string literals can be quoted only within single quotation marks because a string quoted within double quotation marks is interpreted as an identifier.

• MySQL Reference Manual 8.2. Identifiers

The identifier quote character is the backtick (“`”). If the ANSI_QUOTES SQL mode is enabled, it is also permissible to quote identifiers within double quotation marks.