Before Starting• Data Integrity• Data Types• Record (line, tupel)• Field (attribute, column)• Table (file, relation)• Data Dictionary (repository, metadata)• Backup & Recovery• DataWarehouse, DataMart, DataMining

Database Design Guidelines

• What is the purpose of the database?

• Design the tables (ERD on paper)

• Decide which fields to include for each table (datadictionary)

• Create the relationships between tables

• And then start the implementation

CASE 1

Bogus University hired you to design a database for them. They would like to keep track of each student, classes, and rooms so that they would like to be able to find which student is taking which classes or which room is available on a given day, etc. Assume each class can only be thought by a single instructor.

Design the Tables

Students Classes

Rooms ???

Decide which fields to include for each table

StudentsStudent_ID, Student_Name, Student_Phone, Student_Address

ClassesClass_ID, Class_Name, Credits, Instructor, Prerequisite, Days, Time, Room_ID

RoomsRoom_ID, Building, Number

???

Create the relationships between tables

• Determine the relationship types first.• One-To-One

• One-To-Many

• Many-To-Many

• Resolve Many-To-Many relationship in 2 One-To-Many relationships

• Keep on asking yourself “One … can (have, teach, purchase, etc.) many …, but one …cannot (have, teach, purchase, etc.) many …

Create the relationships between tables (Cont’d)

• Select Primary Keys for each table among the Candidates and place the Foreign Keys into tables if necessary.

Tables

Relationships

CASE 2

Sham Bookstore wants you to design a database to keep records of the books they have, their authors, and their publishers. Assume that each book can be published by a single publisher and the order of authors does not matter.

Design the Tables

Books Authors

Publishers ???

Decide which fields to include for each table

BooksISBN, Book_Name, Pages

AuthorsAuthor_ID, Author_Name

PublishersPublisher_ID, Pub_Name, Pub_Phone, Pub_Address

???

Create the relationships between tables

• Can one book be published by many publishers?

• Can one publisher publish many books?

• Can one book have many authors?

• Can one author have many books?Aha!.

Tables

Relationships

SQLStructured Query Language

SELECT fieldname1, fieldname2…fieldnameN

FROM table1, table2…tableM

WHERE (Table Joins)

AND (any specifications, eg. students living in Balto City.)

GROUP BY (used if an aggregate function exist in select clause)

HAVING (any specifications about aggregate functions)

ORDER BY fieldname2, fieldname1;

SQL Examples

List all student names and phone #s in alphabetical order

SELECT Student_Name, Student_Phone

FROM Students

ORDER BY Student_Name;

SQL ExamplesList all student names and phone #s of students whose ID is larger than 233000 in descending alphabetical order

SELECT Student _ID, Student_Name, Student_PhoneFROM StudentsWHERE Student_ID > 233000ORDER BY Student_Name;

SQL Examples

List all book names and publisher names

SELECT Book_Name, Pub_Name

FROM Books, Publishers

WHERE Books.Publisher_ID = Publishers.Publisher_ID;

SQL Examples

List all book names and publisher names of books smaller than 300 pages.

SELECT Book_Name, Pub_Name

FROM Books, Publishers

WHERE Books.Publisher_ID = Publishers.Publisher_ID

AND Pages < 300;