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 [e-mail] 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: [e-mail]

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:

1. George, Batteries
2. 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.