7. Forming a 2NF database
Going on with the concert table
|Wembley||Girls Aloud||53000||12334||Girl band|
|NEC||Leona Lewis||45000||66433||Female soloist|
|NEC||Girls Aloud||76090||53789||Girl band|
This table needs to be split so that non-dependent attributes are removed and only stored once.
In this case a 'style' table is formed that has Artist as the simple primary key
|Girls Aloud||Girl band|
|Leona Lewis||Female soloist|
Now the rule for 2NF is being met by both tables - every non-key attribute is depending on the complete primary key. There is no redundant data.
challenge see if you can find out one extra fact on this topic that we haven't already told you
Click on this link: Compound primary keys