Download Intro to Databases

INTRODUCTION TO
DATABASES
CS 260
Database Systems
Course Outline

SQL queries
DML Select (SELECT)
 DDL (CREATE, ALTER, DROP)
 DML Action (INSERT, UPDATE, DELETE)







User authentication
Data modeling and normalization
Transaction processing
Stored DBMS programs
Scaling and performance
Distributed databases
Why Study Database Systems?

Important

The back end of many important systems





Good job experience



Web-based e-commerce (e.g. amazon.com, imdb.com)
Scientific sites (e.g. protein sequences)
Real-time systems (e.g. air-traffic control)
Business systems (e.g. banking)
Many jobs require database systems experience
Oracle DBAs hired at >$80K, often make >$100K
A lot of data out there





Facebook – over 100 petabytes
Amazon – over 90 pb
Google processes over 20pb per day
AT&T (323 TB, 2010)
World Data Center for Climate (6+ PB, 2010)
Why Study Database Systems?

As it relates to UWEC courses
 CS268
 Use
SQL and JDBC
 CS355
& CS485 (SE I and II)
 Project(s)
 Any
might use databases
CS course might use a database!
Overview



Data management
Database system architectures
Database vocabulary & history
Data Management

"Real" computer applications tend to have:
 Large
volumes of data
 Different types of data
 Data with complex relationships
“Old” Approach to Data Management



File-based
Decentralized
Each application has its own data files
Data
File 1
Application
1
Data
File 2
Application
2
Problems with file based approach?


Duplicate data
Redundant data
 Becomes




inconsistent over time
Requires custom programs to create, update, and
retrieve data from files
Transaction atomicity
Concurrent access issues
Security
DBMS Approach to Data Management



Data is viewed as a shared organizational resource
Centralized
All applications interact with a single centralized
database
Application
1
Database
Application
2
What is a Database?

Components
 Data
files
 Database Management System (DBMS)
Application
1
Database
Data
Files
DBMS
Application
2
What is the DBMS?

Set of programs that perform…

Basic data handling tasks

Insert, Update, Delete, Retrieve
Creating atomic transactions
 Enabling/disabling concurrency
 Database administration tasks



Applications interact only with the DBMS


Creating users, creating objects, enforcing security, creating
backups, …
Never interact directly with the data files
Major players today:

Oracle, SQL Server, DB2, MySQL
Overview



Data management
Database system architectures
Database vocabulary & history
Database System Architectures



Single-tier
2-tier
N-tier
Single-Tier Databases
 Personal
computer-based
Applications and database run on the same local computer
 Example: Access, Filemaker
 What are the limitations?

Host Computer (microcomputer)
Database
Database
Applications
Single-Tier Databases
 Mainframe-based
(host)
 Applications
& database run on the same host computer
 Mainly used in legacy systems
Host Computer
Database
Database
Applications
Network
Terminals
2-Tier (Client/Server)
 DBMS
runs on a server
 Client applications run on the clients

Example: Oracle (server) + SQL Developer (client)
Client Workstations
Database
Applications
Database Server
Database
Network
Database
Applications
Database
Applications
N-Tier Database Systems

N-tier system places each service type on a
different host
Database Server
Middle-tier Server(s)
(Web server)
Client Workstations
(Browser)
User
Services
Database
Business
Services
User
Services
User
Services
Sample Database (CANDY)
CANDY_CUSTOMER CUST_ID
CUST_NAME
CUST_TYPE
CUST_ADDR
CUST_ZIP
CUST_PHONE USERNAME PASSWORD
1 Jones, Joe
P
1234 Main St.
91212 434-1231
jonesj
2 Armstrong,Inc.
R
231 Globe Blvd.
91212 434-7664
armstrong
3 Sw edish Burgers
R
1889 20th N.E.
91213 434-9090
sw edburg
4 Pickled Pickles
R
194 CityView
91289 324-8909
pickpick
5 The Candy Kid
W
2121 Main St.
91212 563-4545
kidcandy
6 Waterman, Al
P
23 Yankee Blvd.
91234
w ateral
7 Bobby Bon Bons
R
12 Nichi Cres.
91212 434-9045
bobbybon
8 Crow sh, Elias
P
7 77th Ave.
91211 434-0007
crow el
9 Montag, Susie
P
981 Montview
91213 456-2091
montags
10 Columberg Sw eets W
239 East Falls
91209 874-9092
columsw e
1234
3333
2353
5333
2351
8900
3011
1033
9633
8399
CANDY_PURCHASE
PURCH_ID
CANDY_CUST_TYPE
PROD_ID
CUST_ID
PURCH_DATE DELIVERY_DATE POUNDS
STATUS
1
1
5
28-Oct-04
28-Oct-04
3.5 PAID
CUST_TYPE_ID
CUST_TYPE_DESC
2
2
6
28-Oct-04
30-Oct-04
15 PAID
P
Private
3
1
9
28-Oct-04
28-Oct-04
2 PAID
R
Retail
3
3
9
28-Oct-04
28-Oct-04
3.7 PAID
Wholesale
4
3
2
28-Oct-04
5
1
7
29-Oct-04
29-Oct-04
3.7 NOT PAID
5
2
7
29-Oct-04
29-Oct-04
1.2 NOT PAID
5
3
7
29-Oct-04
29-Oct-04
4.4 NOT PAID
6
2
7
29-Oct-04
W
CANDY_PRODUCT
PROD_ID
PROD_DESC
PROD_COSTPROD_PRICE
3.7 PAID
3 PAID
1 Celestial Cashew Crunch
$
7.45
$
10.00
7
2
10
29-Oct-04
14 NOT PAID
2 Unbrittle Peanut Paradise
$
5.75
$
9.00
7
5
10
29-Oct-04
4.8 NOT PAID
3 Mystery Melange
$
7.75
$
10.50
8
1
4
29-Oct-04
4 Millionaire’s Macadamia Mix
$
12.50
$
16.00
8
5
4
29-Oct-04
5 Nuts Not Nachos
$
6.25
$
9.50
9
5
4
29-Oct-04
29-Oct-04
1 PAID
7.6 PAID
29-Oct-04
3.5 NOT PAID
Overview



Data management
Database system architectures
Database vocabulary & history
Basic Database Vocabulary
PROD_ID



PROD_DESC
PROD_COST
PROD_PRICE
1 Celestial Cashew Crunch
$
7.45
$
10.00
2 Unbrittle Peanut Paradise
$
5.75
$
9.00
3 Mystery Melange
$
7.75
$
10.50
4 Millionaire’s Macadamia Mix
$
12.50
$
16.00
5 Nuts Not Nachos
$
6.25
$
9.50
Field: column of similar data values
Record*: row of related fields
Table*: set of related rows
• Mathematical terms for record and table: tuple and relation
Database History


All pre-1960’s systems used file-based data
First database: Apollo project
 Goal:
No duplicate data in multiple locations
 Used a hierarchical structure
 Created relationships using pointers
 Pointer:
hardware address
Example Hierarchical Database
UNIVERSITY_STUDENT
Student
ID
Student
LastName
Student
Student
FirstName MI
5000
Nelson
Amber
S
5001
Hernandez
Joseph
P
5002
Myers
Stephen
R
Pointers to Course Data*
UNIVERSITY_COURSE
CourseID
Course
Name
Course
Title
100
MIS 290
Intro. to Database
Applications
101
MIS 304
Fundamentals of
Business
Programming
102
MIS 310
Systems Analysis
& Design
* Hex number
referencing data’s
physical location on
hard drive
Problems with Hierarchical Databases
Relationships are all one-way; to go the other way,
you must create a new set of pointers
 Pointers are hardware-specific



VERY hard to move to new hardware
Applications must be custom-written

Usually in COBOL
Relational Databases

Circa 1972
E.J. Codd
 “Normalizing” relations




Goal: No redundant data
Stores data in a tabular format
Creates relationships by sharing key fields
Key Fields

Primary key: field that uniquely identifies a record
 Often
abbreviated “PK”
UNIVERSITY_INSTRUCTOR
Primary keys
InstructorID
Instructor
LastName
Instructor
FirstName
1
Black
Greg
2
McIntyre
Karen
3
Sarin
Naj
Class Discussion


What is the primary key of each table in the
CANDY database?
How can you tell if a field is a primary key?
Sample Database (CANDY)
CANDY_CUSTOMER CUST_ID
CUST_NAME
CUST_TYPE
CUST_ADDR
CUST_ZIP
CUST_PHONE USERNAME PASSWORD
1 Jones, Joe
P
1234 Main St.
91212 434-1231
jonesj
2 Armstrong,Inc.
R
231 Globe Blvd.
91212 434-7664
armstrong
3 Sw edish Burgers
R
1889 20th N.E.
91213 434-9090
sw edburg
4 Pickled Pickles
R
194 CityView
91289 324-8909
pickpick
5 The Candy Kid
W
2121 Main St.
91212 563-4545
kidcandy
6 Waterman, Al
P
23 Yankee Blvd.
91234
w ateral
7 Bobby Bon Bons
R
12 Nichi Cres.
91212 434-9045
bobbybon
8 Crow sh, Elias
P
7 77th Ave.
91211 434-0007
crow el
9 Montag, Susie
P
981 Montview
91213 456-2091
montags
10 Columberg Sw eets W
239 East Falls
91209 874-9092
columsw e
1234
3333
2353
5333
2351
8900
3011
1033
9633
8399
CANDY_PURCHASE
PURCH_ID
CANDY_CUST_TYPE
PROD_ID
CUST_ID
PURCH_DATE DELIVERY_DATE POUNDS
STATUS
1
1
5
28-Oct-04
28-Oct-04
3.5 PAID
CUST_TYPE_ID
CUST_TYPE_DESC
2
2
6
28-Oct-04
30-Oct-04
15 PAID
P
Private
3
1
9
28-Oct-04
28-Oct-04
2 PAID
R
Retail
3
3
9
28-Oct-04
28-Oct-04
3.7 PAID
Wholesale
4
3
2
28-Oct-04
5
1
7
29-Oct-04
29-Oct-04
3.7 NOT PAID
5
2
7
29-Oct-04
29-Oct-04
1.2 NOT PAID
5
3
7
29-Oct-04
29-Oct-04
4.4 NOT PAID
6
2
7
29-Oct-04
W
CANDY_PRODUCT
PROD_ID
PROD_DESC
PROD_COSTPROD_PRICE
3.7 PAID
3 PAID
1 Celestial Cashew Crunch
$
7.45
$
10.00
7
2
10
29-Oct-04
14 NOT PAID
2 Unbrittle Peanut Paradise
$
5.75
$
9.00
7
5
10
29-Oct-04
4.8 NOT PAID
3 Mystery Melange
$
7.75
$
10.50
8
1
4
29-Oct-04
4 Millionaire’s Macadamia Mix
$
12.50
$
16.00
8
5
4
29-Oct-04
5 Nuts Not Nachos
$
6.25
$
9.50
9
5
4
29-Oct-04
29-Oct-04
1 PAID
7.6 PAID
29-Oct-04
3.5 NOT PAID
Special Types of Primary Keys

Composite PK: made by combining 2 or more fields to create
a unique identifier

Consider the CANDY_PURCHASE table…
Composite PK

Surrogate PK: ID generated by the DBMS solely as a unique
identifier (not done in above example, but likely in
CANDY_CUSTOMER and CANDY_PRODUCT)
Key Fields (continued)

Foreign key


Field that is a primary key in another table
Serves to create a relationship
UNIVERSITY_INSTRUCTOR
Primary keys
InstructorID
Instructor
LastName
Instructor
FirstName
1
Black
Greg
2
McIntyre
Karen
3
Sarin
Naj
Foreign keys
UNIVERSITY_STUDENT
StudentID
Student
LastName
Student
FirstName
StudentMI
AdvisorID
5000
Nelson
Amber
S
1
5001
Hernandez
Joseph
P
1
5002
Myers
Stephen
R
3
Alternative to Foreign Keys


Repeat data values for every record
Problems
 Takes
extra space
 Redundant data becomes inconsistent over time
UNIVERSITY_STUDENT
StudentID Student
LastName
Student
FirstName
StudentMI
AdvisorLast
Name
AdvisorFirst
Name
5000
Nelson
Amber
S
Black
Greg
5001
Hernandez
Joseph
P
Black
Gregory
5002
Myers
Stephen
R
Sarin
Naj
Class Discussion



What are the foreign keys in the CANDY database?
Does a table HAVE to have foreign keys?
How can you tell if a field is a foreign key?
Sample Database (CANDY)
CANDY_CUSTOMER CUST_ID
CUST_NAME
CUST_TYPE
CUST_ADDR
CUST_ZIP
CUST_PHONE USERNAME PASSWORD
1 Jones, Joe
P
1234 Main St.
91212 434-1231
jonesj
2 Armstrong,Inc.
R
231 Globe Blvd.
91212 434-7664
armstrong
3 Sw edish Burgers
R
1889 20th N.E.
91213 434-9090
sw edburg
4 Pickled Pickles
R
194 CityView
91289 324-8909
pickpick
5 The Candy Kid
W
2121 Main St.
91212 563-4545
kidcandy
6 Waterman, Al
P
23 Yankee Blvd.
91234
w ateral
7 Bobby Bon Bons
R
12 Nichi Cres.
91212 434-9045
bobbybon
8 Crow sh, Elias
P
7 77th Ave.
91211 434-0007
crow el
9 Montag, Susie
P
981 Montview
91213 456-2091
montags
10 Columberg Sw eets W
239 East Falls
91209 874-9092
columsw e
1234
3333
2353
5333
2351
8900
3011
1033
9633
8399
CANDY_PURCHASE
PURCH_ID
CANDY_CUST_TYPE
PROD_ID
CUST_ID
PURCH_DATE DELIVERY_DATE POUNDS
STATUS
1
1
5
28-Oct-04
28-Oct-04
3.5 PAID
CUST_TYPE_ID
CUST_TYPE_DESC
2
2
6
28-Oct-04
30-Oct-04
15 PAID
P
Private
3
1
9
28-Oct-04
28-Oct-04
2 PAID
R
Retail
3
3
9
28-Oct-04
28-Oct-04
3.7 PAID
Wholesale
4
3
2
28-Oct-04
5
1
7
29-Oct-04
29-Oct-04
3.7 NOT PAID
5
2
7
29-Oct-04
29-Oct-04
1.2 NOT PAID
5
3
7
29-Oct-04
29-Oct-04
4.4 NOT PAID
6
2
7
29-Oct-04
W
CANDY_PRODUCT
PROD_ID
PROD_DESC
PROD_COSTPROD_PRICE
3.7 PAID
3 PAID
1 Celestial Cashew Crunch
$
7.45
$
10.00
7
2
10
29-Oct-04
14 NOT PAID
2 Unbrittle Peanut Paradise
$
5.75
$
9.00
7
5
10
29-Oct-04
4.8 NOT PAID
3 Mystery Melange
$
7.75
$
10.50
8
1
4
29-Oct-04
4 Millionaire’s Macadamia Mix
$
12.50
$
16.00
8
5
4
29-Oct-04
5 Nuts Not Nachos
$
6.25
$
9.50
9
5
4
29-Oct-04
29-Oct-04
1 PAID
7.6 PAID
29-Oct-04
3.5 NOT PAID
Rules for Relational Database Tables


Every record has to have a non-NULL (or “nonempty”) and unique PK value
Every FK value must be defined as a PK in its
parent table