Database

Database management
Homework 1

Chapter 1. Getting started

A. Create a simple list of owners and properties.

B. Describe modification problems.

There are three problems. First is deletion problem, second is update problem, third is insertion problem. Deletion problem is when you want to delete data, you may lost too much data. Update problem is when you want to update data, the sheet may have inconsistent data. Last insertion problem is when you want to insert some data, you must insert a row with incomplete values, called null values.

C. Split the list into tables. Create appropriate ID columns.

Create appropriate ID columns. : ID column is ID column.

Use a linking column.

Deletion problem

Insert problem

Update problem

D. Create a simple list of owner, properties, services.

E. Illustrate modification problems to maintain the list from part D.
There are three problems. First is deletion problem, second is update problem, third is insertion problem. F. Split the list from part D.

Use a linking column.

Deletion problem

Insert problem

Update problem

Chapter 2. The relation model

A. Using these data, state assumptions about functional dependencies. Justify your assumptions

Gardern Glory(PropertyName, Type, Street, City, ZIP, ServiceDate, Description, Amount )

PropertyName → Type, Street, City, ZIP , Description, Amount
(Type, Street, City, ZIP, Amount) → PropertyName

B. Comment on the appropriateness of the following designs

9. PROPERTY(PropertyID, PropertyName, Type, Street, City, ZIP)
SERVICE(ServiceID, ServiceDate, Description, Amount, PropertyID).

C. SERVICE-FEE(PropertyID, ServiceID, Description, Amount)
Add this table to what you consider to be the best design in your answer to part B.

Modify the tables from part B as necessary to minimize the amount of data duplication. PROPERTY(PropertyID, PropertyName, type, street, city, zip, amount)