PHP & MYSQL selection - php

Question

Ok folks. I have a Table categories with id, categoryname.
categories has: id=1 categoryname = batteries, id=2 categoryname = flashes, id=3 categoryname glasses.
The Second table is users. Users have id, user_eimal, my_choices.
Every user has store into my_choices the category name that wants to appear.
So for example user George with user_email xxxxx#xxx.com has store in my_choices: batteries,glasses
Now i want to bring up records from table products where categoryname is the values that user george has stored into my_choices.
Products has id, p_title, categoryname
for example i want to:
<?php
$usenmail = $_SESSION['SESS_EMAYL_NAME'];
$q1 = "SELECT * FROM categories WHERE id = '$id'";
$q2 = mysql_query($q1, $connectiondb) or die(mysql_error());
$results = mysql_fetch_assoc($q2);
$my_choices = $results['my_choices']; //That means $my_choices = batteries,glasses
//Now i want to select fom my table poducts only the categories (batteries,glasses)that user has store.
$trt = mysql_query ("select * from products where categoryname = batteries,glasses");
while($apst = mysql_fetch_assoc($trt)) {
echo '<div style="color: #000; float: left;">Productname: '.$['apst'].'</div>';
echo '<br>';
}
?>

Answer 1

You want to use a join table so you can have a many-to-many relationship. Your current structure is better suited to each user only having ONE choice.
What you want are three tables:
Users (userID, user_name, user_email)
Categories (categoryID, category_name)
Users_Categories (userID, categoryID)
So to use your example, your three tables would look like this (if anyone knows a better way to demonstrate SQL tables on here, please let me know):
Users
userID: 1 | user_name: George | user_email: george#example.com
Categories
categoryID: 1 | category_name: batteries
categoryID: 2 | category_name= flashes
categoryID: 3 | category_nameglasses.
Users_Categories
userID: 1 | categoryID: 1
userID: 1 | categoryID: 3
You would then use a select statement with a join clause to get George and his categories:
SELECT
user_name,
category_name
FROM
Users
LEFT JOIN Users_Categories USING (userID)
LEFT JOIN Categories USING (categoryID)
WHERE
userID = 1
This would return two rows in the result:
George, Batteries
George, Glasses
Depending on what you want to do with that data, it may be better to also select the userID.
If you want a query that will only return one row with all of the information, it gets a little trickier. You have to use the GROUP BY functionality. That would look like this:
SELECT
user_name,
GROUP_CONCAT (category_name ',')
FROM
Users
LEFT JOIN Users_Categories USING (userID)
LEFT JOIN Categories USING (categoryID)
GROUP BY
userID
WHERE
userID = 1
For your final question about products, you would follow the same logic with more joins. Your Products table wants to have a productID, product_name, and categoryID.

Answer 2

$trt = mysql_query ("select * from products where categoryname = 'batteries' OR categoryname = 'glasses'");

Answer 3

Use explode function
$array = explode(','$my_choices);
now array[0] and array[1] have the 2 values. then use
$result = mysql_query ("select * from products where categoryname = '".$array[0]."' OR categoryname = '".$array[1]."'");

Answer 4

In your case use select statement as,
select * from products where categoryname in ( 'batteries','glasses');
ie,
//add quotes to category names (if ids you dont neeed these 2 lines)
$cats=explode(',',$my_choices);
$strcats = "'" . join("', '", $cats) . "'";
$trt = mysql_query ("select * from products where categoryname in ($strcats));
My suggestion to use category ids instead of category names.