Homework SourseList the two candidate keys for the table List the nonprime
)List the two candidate keys for the table
)List the non-prime attributes for the table
)List the non-trivial functional dependencies for the table. Please include even functional dependencies whose left-hand side is a superkey
)Which of the following normal forms is the table in? 1nf,2nf,3nf,bcnf
)for each normal form which it is not in,demonstrate why it is not in that normal form by describing the normal form violation for that normal form
| ITEM | COLOR | PRICE | QUANTITY |
| pencil | yellow | 1 | 12 |
| pencil | black | 1 | 6 |
| pen | white | 1 | 8 |
| pen | black | 1 | 8 |
| paper | white | 3 | 20 |
| paper | yellow | 4 | 20 |
Solution
1) There is no candidate key for this table, as there is no column whose entries uniquely identify a record in the table. However, there are composite keys, i.e. the combination of keys that uniquely identify each record.
ITEM + COLOR is an example of composite key, any combination of those is a new record.
2) All the attributes in the table are Non-Prime attributes, as they don\'t belong to any candidate key.
3) I\'m skipping this one intentionally
4) The table is in First Normal Form (1NF) as no two rows contain repeating groups of information.
5) It\'s not 2NF as there is a dependancy of PRICE on ITEM and the only rule for 2NF is that there should not be any functional dependancies. Therefore, it can\'t be 3NF either, for 3NF it should be 2NF also.
