1, first of all, the punctuation is not correct: select c.price code, c.unit price, c.amount from hospitalization 200801 c.price of services d where c.price code = d.code and d.price of medical services <> c.unit price
2, select c.price code, c.unit price, c.amount from hospitalization200801 statement does not use the table "hospitalization200801"
3, there is also the relationship between your table, I do not know how to define.