SQL-创建数据透视表

Question

I'm trying to create a pivot table from data in a number of tables, but I can't get it to work. This is the database structure:

So the tables would look like:

What I would like to create is a pivot table combining all sales data from customers per product like this:

(This data is to be fed into a different system which requires this as input, so I can't change the format)

However, I have no idea how to accomplish this. I tried this:

select distinct c.name, 
       p.name,
       sum(p.price)        
FROM customer c
  left join sale s on c.customerId = s.customerId
  left outer join product p ON s.productId = p.productId
group by s.productId, s.customerId

I know it's not much, but I'm having a hard time wrapping my head around it. Can anyone help me get on track?

Cheers, CJ

Answer 1

Its very easy, you can pivot it by custom case when statements:

select c.name, 
sum(CASE WHEN p.name = 'Product X' THEN p.price ELSE 0 END) AS "Product X",
sum(CASE WHEN p.name = 'Product Y' THEN p.price ELSE 0 END) AS "Product Y",
sum(CASE WHEN p.name = 'Product Z' THEN p.price ELSE 0 END) AS "Product Z"
    FROM customer c
      left join sale s on c.customerId = s.customerId
      left outer join product p ON s.productId = p.productId
    group by c.customerId, c.name