Homework SourseExamine the following relation and answer the following ques
Examine the following relation and answer the following questions. Assume these are the values that exist for all time (e.g., the toys shown always cost the amount shown) and that boys with the same name are the same person.
AGE
PRICE
6
5
6
5
5
6
5
Is this relation in at least 1NF? Why or why not?
Assuming the values shown are the only possible tuples for all time, what is the primary key of the initial relation? Remember that a primary key must be unique and not null.
What normal form is this relation currently in?
Describe the specific modification anomalies that exist if we DELETE the tuple containing Stewart.
If necessary, decompose the initial relation into a set of non-loss 3NF relations by showing the relations, attributes, and tuples. Show complete relations with attribute headings and all data values in the tuples of your relations. Determine the number of 3NF relations you end up with after normalization, write this number, and then circle the number.
| BOY | GROUP | AGE | TOY | CATEGORY | PRICE |
| Charlie | 6 year olds | 6 | Soccer ball | Sports | 18.44 |
| Jimmy | 5 year olds | 5 | Hammer | Tools | 7.99 |
| Robert | 6 year olds | 6 | Baseball | Sports | 8.99 |
| Jimmy | 5 year olds | 5 | Soccer ball | Sports | 18.44 |
| Jimmy | 5 year olds | 5 | Wrench | Tools | 6.99 |
| Charlie | 6 year olds | 6 | Baseball | Sports | 8.99 |
| Stewart | 5 year olds | 5 | Oracle | Computer Software | 399.99 |
Solution
We say that database is in first normal form if it satisfies the following conditions:
1. Contains only atomic values
2. There are no repeating groups
The above given database is in first normal form because it satisfies the above two mentioned conditions.
The primary key of the given relation is (Boy+Toy) because it identifies all the tuples of the relation uniquely and its
value is not null.
The relation is in \"First Normal Form(1NF)\" and not in the 2NF and 3NF because the attributes are not fully dependent on
whole primary key. For Example, if we want to know the price of any toy then it can just be determined from attribute toy
which constitutes the partial part of the primary key.
Now if we delete the tuple containing \"Stewart\" there will be no effect on the realtional table because:
1. Since Stewart is the unique identifier in the attribute named \"Boy\". So, there will be no effect on the values of attribute Boy.
2. Now since stewart has \"Oracle\" as an identifier for attribute \"Toy\" and there is no other entry with the same identifier on any
other tuple. Therefore there will be no effect on \"Toy\" too.
3. Same goes with the attribute \"Category\" as computer science is uniquely defined for stewart and after deletion there will be no
effect on the relation.
