Article claims the following table is not in 1NF

1. One site claims the following table is not in first normal form – but the definition for 1NF just says that data shouldn’t contain repeating groups of fields. And it’s quite obvious that there are no repeating columns in the following table, since I wouldn’t consider Last_name column being same as Cust_lastname or Address same as Cust_address ( but I would consider ORDER ( ORDER_ID, ITEM1, ITEM2, ITEM3 ) to have repeating columns ) …

COMPANY_DATABASE ( Emp_id#, Last_name, First_name, Address, City, State, Position, Cust_id#, Cust_lastname, Cust_firstname, Cust_address, Cust_city, Ord_num, Ord_date, Prod_id, Cost )

2) My book claims that if table is not normalized, then primary key can’t be made out of just one attribute. But how can that ALWAYS be true, since even if a table has multi valued attributes or duplicative columns, we could still have an attribute ( ORDER_ID ) that would uniquely identify the row:

ORDER ( ORDER_ID, ITEM1, ITEM2, ITEM3 ) Now even though the above table has repeating columns ( ITEM1, ITEM2, ITEM3 ), ORDER_NUM column would still be able to uniquely identify the row!

Similarly, if ITEM column is multi valued, we could still have ORDER_ID as unique key:

ORDER ( ORDER_ID, ITEM ) thank you Received on Wed Oct 22 2008 - 20:38:01 CEST