sk, the link of fact to dimension

A query on a star schema links its surrogate keys, as seen in the query's WHERE clause.

SELECT order_number, sales_amount, order_quantity
FROM sales_fact sf, order_dim od, customer_dim cd, product_dim pd, date_dim dd
WHERE
sf.order_sk = od.order_sk
AND sf.customer_sk = cd.customer_sk
AND sf.product_sk = pd.product_sk
AND sf.date_sk = dd.date_sk