Sql Left join什么都不返回

Question

I want to join table of products and table of orders in a way that all products are listed and price of all ordered product by current user are shown (However some of those prices are 0 because there is no order submitted for that product).

As the user confirms the list, An invoiceId is produced for all products in this list. So the invoiceId is null in this step yet (which is my question).

There are many products in first table but why the output is empty?

Table products:

id | price

Table orders:

id | ProductId | member | invoiceId

(I added orders.member is null regarding to this question but no chance yet):

Select * from products left join orders 
on products.id=orders.productId 
where (orders.member='"&request.cookies("member")&"' or  orders.member is null) 
and orders.invoiceId is null

Edit: My Guess: There are also orders of other members. Does they violate current where condition ?

Answer 1

Your condition is on the second table. Hence, it should go in the on clause:

Select *
from products p left join
     orders o
    on p.id = o.productId and
       o.member='"&request.cookies("member")&"'
where o.invoiceId is null;