I have table users -
id | name | |
---|---|---|
1 | tamaghna | tamaghna@g |
2 | arunima | arunima@g |
3 | rajiv | rajiv@g |
I have another table products -
id | name | price |
---|---|---|
1 | Amul Milk | 10.00 |
2 | Amul Butter | 20.00 |
3 | Amul Cheese | 30.00 |
And the final table cart
id | user_id | product_id |
---|---|---|
1 | 1 | 1 |
2 | 1 | 3 |
3 | 2 | 1 |
What I want is a cross of two tables referencing the cart table -
product name | user name | bought? |
---|---|---|
Amul milk | tamaghna | 10.00 |
Amul Butter | tamaghna | NULL |
Amul Cheese | tamaghna | 30.00 |
Amul milk | arunima | 10.00 |
Amul Butter | arunima | NULL |
Amul Cheese | arunima | NULL |
Amul milk | rajiv | NULL |
Amul Butter | rajiv | NULL |
Amul Cheese | rajiv | NULL |
I tried
select
t1.name, t1.email, t3.name, t3.price
from Users t1
left outer join cart t2
on t1.id = t2.user_id
left outer join products t3
on t2.product_id = t3.id
but no luck doesn't get the actual table out as it required. Any help?
You would typically cross join
users and products, then bring the cart
table with a left join
on the columns from both reference tables:
select u.name user_name,
p.name product_name, p.price product_price,
(c.id is not null) product_is_in_user_cart
from users u
cross join products p
left join cart c on c.user_id = u.id and c.product_id = p.id
This gives you a resultset that contains the user name, the product name and price, and a 0
/1
column that indicates whether that product can be found in the cart of the user (which seems more easy to understand than to display the price of products that are in cart only, but you can still get there with case
if you want).
Note that I changed the table aliases to make them more meaningful.