PHP, trying to get $_POST['var'] into table as text - php

Question

i'm having trouble with the code below. it's been simplified to show the problem. i use a loop because the input names are identical and need to create multiple new rows in a mysql table. the problem is i'm using $_POST['name'][$i] and the table won't accept because it doesn't see it as 'text?, ...i think.
like i said, code's been greatly simplified.
for($i=0;$i<count($_POST['url']); $i++) {
$sql = 'INSERT INTO urls (url) VALUES ('. $_POST['url'][$i].')';
if(!mysql_query($sql)) {
echo "error " . mysql_error();
}
}
i tried to rememdy with this -
$sql = 'INSERT INTO urls (url) VALUES ('. '"'. $_POST['url'][$i].'"'. ')';
if i do this it works, there is no error
$sql = 'INSERT INTO urls (url) VALUES (' " hello " ')';
this is probably a newbie type mistake, right? thanks for any help with this.

Answer 1

A cleaner way (and the errors are fixed):
$urls = (isset($_POST['url']) && is_array($_POST['url'])) ? $_POST['url'] : array();
foreach($urls as $url) {
if(!is_string($url)) {
continue;
}
$sql = "INSERT INTO urls (url) VALUES ('" . mysql_real_escape_string($url) . "')";
if(!mysql_query($sql)) {
echo "error " . mysql_error();
}
}
Making sure the $_POST['url'] is an array will keep from trying to treat a non array (or non-existent key) as an array. The is_string is to protect from a user trying to throw in a sub array to get PHP to throw a "using array as string" notice. The escape is to avoid SQL injection, and the single quotes added are so MySQL knows it's a string.

Answer 2

You simply need to add quotes around the POSTed value in your MySQL query like below. Also, if you don't escape the input, it's a massive SQL injection vulnerability:
$data = mysql_escape_string($_POST['url'][$i]);
$sql = 'INSERT INTO urls (url) VALUES ("'.$data.'")';
The query breaks MySQL because MySQL thinks your post value is supposed to be numeric without the quotes.

Answer 3

It would be helpful to see that actual error message returned by mysql_error() but I think your problem is that you're not providing the $_POST value to the sql query as thought it's text.
try replacing
$sql = 'INSERT INTO urls (url) VALUES ('. $_POST['url'][$i].')';
with
$sql = "INSERT INTO urls (url) VALUES ('". mysql_real_escape_string($_POST['url'][$i]) ."')";

Answer 4

You need to escape your $_POST variables before you insert them via an SQL statement, preferably using the mysql_real_escape_string() function to fortify your query against SQL injection attacks.

Answer 5

Answer provided by Corbin is good - however try not to fire insert queries in a loop.
You could create the sql query as one string and then fire the insert query once.
You could change your insert statement from
insert into table (field) values(1);
insert into table (field) values(1);
To:
insert into table (field) values(1), (2), (3), (4)...
This is a more optimal solution - however mysql has a max length to which it can take sql statements - therefore use your best judgement.

Answer 6

try this statement
$sql = "INSERT INTO urls (url) VALUES ('". mysql_real_escape_string($_POST['url'][$i])."')";