cannot send the string into INSERT query - php

Question

i have json as input
$page = file_get_contents('http://example.com/products.html');
$items = json_decode($page, true);
if i put echo $page; i get smth like this
{
"productlist":[
{
"id":"1",
"cat":"milk",
"prod_name":"happy milk",
"img_url":"http://example.com/milk.jpg"},
{
"id":"2",
"cat":"bread",
"prod_name":"black bread",
"img_url":"http://example.com/bread.jpg"},
then, i want to put it into MySQL DB
foreach($items['productlist'] as $item) {
$id = $item['id'];
$cat = $item['cat'];
mysqli_query($link, "INSERT INTO table (id, cat) VALUES ($id, $cat)") or die(mysql_error());
}
at this stage i get nothing. if i modify code into
foreach($items['productlist'] as $item) {
$id = $item['id'];
mysqli_query($link, "INSERT INTO table (id) VALUES ($id)") or die(mysql_error());
}
i get the table in DB filled - i have two rows with prod id. Ok, i want to insert into table the $cat = food
foreach($items['productlist'] as $item) {
$id = $item['id'];
$cat = 'food';
mysqli_query($link, "INSERT INTO table (id, cat) VALUES ($id, $cat)") or die(mysql_error());
}
yet this does not work, i get null result. but if i modify query into
foreach($items['productlist'] as $item) {
$id = $item['id'];
mysqli_query($link, "INSERT INTO table (id, cat) VALUES ($id, 'food')") or die(mysql_error());
}
i get the result i seek for - tho rows in table, filled with id and cat
id cat
1 food
2 food
does anyone know how to send string value into insert query via variable?

Answer 1

That doesn't work because cat is a String field, need to be between quotes '...'. try this :
mysqli_query($link, "INSERT INTO table (id, cat) VALUES ($id, '$cat')") or die(mysql_error());
or this :
mysqli_query($link, "INSERT INTO table (id, cat) VALUES ($id, ".$cat.")") or die(mysql_error());

Answer 2

First, I would suggest you to learn how to use prepared statements, as you are getting your strings outside of your code (it may contain some mysql injections).
To answer your question, you need to put some quotes around the variable you want to put in your query as it is a string, so mysql can interpret it correctly
mysqli_query($link, "INSERT INTO table (id, cat) VALUES ($id, '$cat')") or die(mysql_error());

Answer 3

Try this
mysqli_query($link, "INSERT INTO table (id, cat) VALUES ($id, ".mysql_real_escape_string($cat).")") or die(mysql_error());