1. CPSC 603 Database Systems Lecturer: Laurie Webster II, Ph.D., P.E.
Introduction to a First Course in Database Systems

2. CPSC 603 Database Systems What is a Database Management System?
Manages very large amounts of data
Supports efficient access to very large amounts of data
Supports concurrent access to v.l.a.d
Supports secure, atomic access to v.l.a.d

3. Relational Database Systems
CPSC 603 Database Systems
Relational Database Systems
Ted Codd in 1970 wrote a famous paper “A Relational Model for large shared data banks”
=> database systems changed significantly!!

4. CPSC 603 Database Systems
Database Systems presented Users with a View of data organized as tables called Relations
In this course we will concentrate primarily on Relational Models of Database Systems

5. Relational Model (Table)
CPSC 603 Database Systems
Relational Model (Table)
acct# name balance
12345 Sally
34567 Sue
…… …… …...

6. Relational Model (Table)
CPSC 603 Database Systems
Relational Model (Table)
* Today Relational Models are used in most
DBMS’s
* The columns of relations (tables) are headed
by attributes (acct#, name, balance, type,….)

7. Relational Model (Table)
CPSC 603 Database Systems
Relational Model (Table)
Rows of the relations(tables) are also called tuples
Tuples are a mathematical term

8. Relational Model (Table) Columns Tuples Rows
CPSC 603 Database Systems
Relational Model (Table)
Columns
Tuples
Rows

9. SQL => Structured Query Language
CPSC 603 Database Systems
SQL => Structured Query Language
SELECT A1, A2, ………., An
FROM r1, r2, ………….., rm
WHERE p
Relational Algebra
A1, A2, ……., An ( p (r1, r2, ………….., rm ) )
p  predicate , Ai  attributes , ri  relations

10. CPSC 603 Database Systems attributes account balance type
savings
rows (tuples) checking
…… ………. ……….
…… => many more tuples, one for each account
at this bank!!!
CPSC 603 Database Systems

11. CPSC 603 Database Systems attributes Accounts accountNo balance type
savings
rows (tuples) checking
…… ………. ……….
SELECT balance
FROM Accounts
WHERE accountNo = 67890;
QUERY: What is the balance of account number
67890 ?
CPSC 603 Database Systems

12. CPSC 603 Database Systems SQL QUERY => SELECT account FROM Accounts
WHERE type = ‘savings’
AND balance < 0;
QUERY: What are the saving accounts with negative
balances?

13. CPSC 603 Database Systems SQL QUERY => SELECT account FROM Accounts
WHERE type = ‘savings’
AND balance < 0;
1. Examine all tuples of the relation Accounts
mentioned in the FROM - clause
2. Pick out those tuples that satisfy some criterion
indicated in the WHERE clause, and
3. Produce as an answer certain attributes of those
tuples, as indicated in the SELECT - clause.

14. CPSC 603 Database Systems Major Components of a DBMS: Query Processor
Storage Manager
Data + Metadata
Transaction Manager
Metadata = information about the structure of the data
If the DBMS is relational then the metadata includes the names of relations, names of attributes, data types for these attributes (e.g., integer or character string of length 20)

15. Schema
Modifications
Queries
Modifications
Query Processor
Transactions Manager
Storage Manager
Data
Metadata

16. CPSC 603 Database Systems DATA MODELS
* Underlying structure of a database is the data
model
structure => data types, relationships,
constraints that should hold
for the data

17. Data Models Object-based logical models Record-based logical models
Physical models

18. Object-Based Logical Model
Entity-Relationship model (ER Models)
The Object-Oriented model
The Semantic Data Model
The Functional Data Model

19. E-R Data Models
E-R Model is based on a perception of a real world that consists of a collection of basic objects called entities and of relationships among these objects
Entity is a “thing” or “object” in the real world that is distinguishable from other objects
i.e. a person is an entity
Relationship is an association among several objects

20. Object-Oriented Model
Object-Oriented Models are based on a collection of objects

21. Record-Based Logical Model
Relational Model (primary focus of this class)
Network Models
Hierarchical Model