7. Forming a 2NF database

Going on with the concert table

CONCERT

Venue Artist Attendance Profit Style
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

CONCERT

Venue Artist Attendance Profit
Wembley Girls Aloud 53000 12334
NEC Leona Lewis 45000 66433
NEC Girls Aloud 76090 53789

STYLE

Artist Style
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

 

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