PHP nested loops with foreign key table - php

Question

This is a multi-part question. My database looks like this:
USERS
-id
-fname
-lname
COMPANIES
-id
-name
-type
PRODUCTS
-id
-product
-restaurant (foreign key to companies id)
-vendor (foreign key to companies id)
-user (foreign key to users id)
-transaction_date
Is this a good way to set up the database? I was thinking of having separate tables for restaurants and vendors but wanted them to use the same login page and rather than have to worry about UNION queries, I just select them by type. They see different information upon login so I have an if statement that says if type = r, show this else show that. Best way?
The second issue comes up when I want to show the information upon login. Say a vendor logs in, they will see a list of all the records that match their vendor id. However, I am seeing too many records because of my nested loop. For example, the table looks like this:
Date--Product--Restaurant--User
I am using this query:
$sql = mysql_query("SELECT products.*, companies.name, CONCAT_WS(' ', users.fname, users.lname) AS fullname FROM products INNER JOIN companies ON products.vendor = companies.id INNER JOIN users ON products.user = users.id WHERE company='$id' AND companies.type='$type'") or die(mysql_error());
$num=mysql_num_rows($sql);
$sql1 = mysql_query("SELECT products.restaurant, companies.name AS cname FROM products INNER JOIN companies ON products.restaurant = companies.id") or die(mysql_error());
$num1=mysql_num_rows($sql1);
$i = 0;
while ($i < $num) {
$j = 0;
while ($j < $num) {
$d = mysql_result($sql,$i,"transaction_date");
$p = mysql_result($sql,$i,"product");
$r = mysql_result($sql1,$j,"cname");
$u = mysql_result($sql,$i,"fullname");
<td><?php echo $d; ?></td>
<td><?php echo $p; ?></td>
<td><?php echo $r; ?></td>
<td><?php echo $u; ?></td>
$j++; }
$i++; }
$id and $type are session created values upon login. There are 4 example records currently in the table. Rather than showing just 4, it shows 16 because the values of $num and $num1 are both 4 and $num is looping $num1 four times.
How can I fix this problem and just show the 4 records?
Thank you for your help. Let me know if you need any clarification on any part.

Answer 1

Your database set-up may need a little rethink.
The reason I think this is that you need to know which company each user is in and you cannot have this within the products table as you have.
I would consider adding the foreign key to the users table like so (assuming one user has one company and one company has many users). I have also made some other suggestions, something like the below:
users
- id
- company_id
- first_name
- last_name
companies
- id
- name
- company_type_id
company_types
- id
- type
products
- id
- product_name
- company_id
transactions
- id
- user_id
- product_id
- transaction_date
they will see a list of all the records that match their vendor
Now you will notice I removed the vendor id from the above tables - This is because the vendor id is the same as the company id. There is no point having two separate relationship id's for the same thing (correct me if I'm mistaken)
So with the above changes we can list these records easily, as so:
<?php
$db = new PDO(/**Connection info here**/);
$stmt = $db->prepare("
SELECT
a.id AS product_id,
a.product_name
FROM
products AS a
INNER JOIN
companies AS b ON b.id = a.company_id
INNER JOIN
company_types AS c ON c.id = b.type_id
WHERE
b.id = :company AND c.id = :companyType
");
$stmt->bindParam(":company", $usersCompanyIdHere, PDO::PARAM_INT);
$stmt->bindParam(":companyType", $usersCompanyTypeHere, PDO::PARAM_INT);
$data = $stmt->execute();
while ($row = $data->fetch()) {
/** List of all the products for given company id**/
}
?>
I have changed you code to use PDO, I don't want to overload you with info here but I cannot stress enough the benefits of using the PDO over native mysql_* functions - Do a Google search, I can see lots of useful and relevant information in the top 10 results.