Question

I have a table for products and a table for users who have bought products. On the products table A there is site_name which determines where the products were bought.

Table B shows the users and what they have bought.

I am using the following to show a list of products bought, by site_name, grouping the product name together.

SELECT product FROM A JOIN B ON A.prod_id = B.prod_id WHERE A.site_name = 'ebay' group by A.product

Table A for products is:

prod_id
site_name
product

Table B for users is:

user_id
prod_id

What i can’t figure out is how to get the number of products bought per line.

e.g. in table A there is

prod_id    site_name    product
-------    ---------    -------
1          ebay         chair
2          amazon       desk
3          ebay         lamp

and on table b

user_id    prod_id
-------    -------
1000         1
1001         2
1002         1
1003         3

So I want to show each line where site_name is ebay and how many products were bought, order by most first like:

chair    2
lamp     1

Answer 1

A minor change to Michael’s query.

SELECT
    products.product,
    COUNT(users.prod_id) AS productsBought
FROM
    A AS products
    INNER JOIN B AS users
        ON products.prod_id = users.prod_id
WHERE products.site_name = 'ebay'
GROUP BY products.product

The above query will not return products that haven’t been bought.