Let's say I have a simple OLTP database with orders, products, and customers:
And from it, I am building a data mart with an orders fact table, product dimension, customer dimension, and date dimension:
When loading the orders table into fact_orders (let's say I was using an SSIS Lookup Transformation to assign the surrogate keys), does that mean that the source of data for the orders would also need to have the natural "foreign key" values that were associated with the order in the OLTP system?
In other words, would the data that's being loaded come from a query like this?
SELECT order_date, -- needed to get date surrogate key customer_name, -- needed to get customer surrogate key product_name, -- needed to get product surrogate key order_number, -- denegenerate dimension, qty_ordered AS order_qty, -- measure total_amount AS order_amount -- measure FROM orders o INNER JOIN customers c ON o.customer_id = c.customer_id INNER JOIN products p ON o.product_id = p.product_id