Do not execute the command or for SQL PHP code - php

Question

Why does the following code not work when I use the command or?
<?php
include "connect.php";
$sort=$_POST["sort"];
$query="SELECT * FROM product WHERE $sort='0' ORDER BY id DESC OR $sort='1' ORDER BY id ASC ";
$stmt = $conn->prepare($query);
$stmt->execute();
$product=array();
while ($row=$stmt->fetch(PDO::FETCH_ASSOC)){
$record["id"]=$row["id"];
$record["title"]=$row["title"];
$product[]=$record;
}
echo JSON_encode($product);

Answer 1

What is it you're trying to attempt here? It looks like you're trying to dump an if else statement within the sql query. That's not the correct way to do it. If I'm correct with what Im saying. You can try something like this
if (Something == SomethingElse) {
$query="SELECT * FROM product WHERE $sort='0' ORDER BY id DESC"
} else {
$query="SELECT * FROM product WHERE $sort='1' $sort='1' ORDER BY id ASC"
}
Something along those routes. Also, I highly suggest you use a foreach statement for your rows instead of assigning them individually.
$query="SELECT * FROM product WHERE $sort='0' ORDER BY id DESC"
foreach ($query as $row) {
$row["id"];
$row["title"];
}
Remember this is just an example, so you'll have to work out the rest of the code yourself. Since you shared so little of what these variables exactly mean its hard for me to understand what you precisely want.
More about Foreach

Answer 2

You can't do that, you can't change the order of SELECT using OR. The OR is only for WHERE statements.
You can try to create one query and next using IF to make one or another query with ORDER BY.
Another thing, be carefully with inject strings from POST directly to your SQL statement, it is very insecure. More on SQL injection.