Brian Harrington
(Slides adapted from material by Dr. Purva Gawde and Dr Anna Bretscher)
Welcome to CSCB20
What is this course?
●
A practical introduction to databases and web app development
Why Databases?
●
It’s how computers organize information
Why Web Apps?
●
It’s how people access information
Course Structure
● Database Design: First 5-6 weeks
● Web Application Design: Next 6-7 weeks
● Weekly Work:
○
○
○
○
○
Lectures: 2 hours per week
Tutorials: 1 hour per week (starting in week 2)
Reading: Approx 1 hour per week
Practice: Approx 2 hours per week
Assignments: Approx 1-2 hours per week
Evaluation
● Term Work (35%)
○ 3 Assignments
■ Assignment 1 - 8%
■ Assignment 2 - 12%
■ Assignment 3 - 15%
● Midterm (25%)
● Exam (40%)
○ Need to score at least 35% on final exam to pass the course)
How To Succeed in CSCB20
●
●
●
●
●
Come to Lecture/Tutorial
Stay on top of material
Do assigned readings
Practice
Have fun!
Lecture Plan
● Databases
○ What/Where/Why/When/How
● Web Applications
○ Very brief overview
● Back to Databases
○ Introduction to Relational Algebra
■ Procedural query language
○ Terminology
Databases: What
● A Database is just a collection of
interrelated data
○ (technically doesn’t have to be
interrelated, just really boring if
it’s not)
A Database
Databases: What
● A Database Management System
(DBMS) is:
Databases
○ One or more databases
○ A set of programs to
DBMS
access/manipulate data
○ Another set of programs to
ensure integrity of data
You (not touching data
directly)
Databases: Why?
● Ummm… to store data?
● But why not just plain text files?
○ Fine for small amounts of data
○ Difficult to format
○ Can’t perform any checks/calculations
● Spreadsheets?
○ Fine for medium amounts of data
○ Designed for single access
○ No redundancy/accuracy checking
<
<
Databases: Why?
● Database transactions are
(or should be) ACID
○ Atomic (all or nothing)
○ Consistent (can’t stop
half way)
○ Isolated (can’t impact
other transactions)
○ Durable (once
committed, stays
committed)
Databases: Where?
● Basically anywhere you have large amounts of structured,
interrelated data that needs concurrent access
○ Retail
○ Manufacturing
○ Banking
○ Universities
○ Travel
○ Telecommunications
Source: Brand Finance (@visualcap)
Databases: Which?
● Many types of DBMS
○ Object-Oriented
○ Network
○ NoSQL
○ Hierarchical
○ Relational (← this is us)
● Why are we using Relational?
○ Commonly Used
○ Cross platform
○ Integrates with common web app software
Relational Database Model
● Data is stored in tables
○ Each row represents a single entity
○ Each column represents a specific attribute
○ Relations between entities can be indicated by shared keys
Ted Codd
Turing Award
1981
Important Aside: Data Abstraction
● The Relational Model is only an abstraction, a collection of
tools for describing data, semantics, relationships and
constraints. The data (probably) isn’t actually held in simple
tables, complex data structures can be used to make things
more efficient, but thanks to abstraction… we don’t have to
care about them (unless we take CSCC43)
Database Languages
● Data Definition Language (DDL)
○ Specify the database schema (tables, attributes,
relations)
● Data Manipulation Language (DML)
○ Access and update data
○ We will be using SQL
Web Applications (A very brief overview)
Web Applications
● Front End: Interacting with the user
○ HTML (put content on the page)
○ CSS (ensure consistent style)
○ JavaScript (add dynamic elements)
● Back End: Interacting with the database/servers/etc
○ JavaScript/Ruby/Java/Python (manipulate user
requests)
○ SQL (interact with DBMS)
BREAK
Relational Databases Introduction
● Some Terminology:
○ Tables(Relations): set of data about a specific
relationship
○ Tuples(Rows): information about a particular entity with
respect to a particular relation
○ Attributes(Columns): The specific values of a relation
○ Schema: Logical design of tables/relations
Relational Databases Introduction
Instructor
name
Course
dept_name office
code
semester enrolment
Harrington CMS
IC342
CSCA20
F
500
Turing
CMS
IC123
CSCA08
F
800
Einstein
Physics
SW999
CSCB20
S
175
Mozart
Music
AA123
PSYA01
F
1000
Freud
Psychology SY234
PHYD01
S
3
Instructor(name, dept_name, office)
Course(code, semester, enrolment)
Relational Databases Introduction
Instructor
ID
name
Course
dept_name office
code
dept_name semester enrolment
12345 Harrington CMS
IC342
CSCA20
CMS
F
500
23456 Turing
CMS
IC123
CSCA08
CMS
F
800
41231 Einstein
Physics
SW999
CSCB20
CMS
S
175
23124 Mozart
Music
AA123
PSYA01
Psychology F
1000
98765 Freud
Psychology SY234
PHYD01
Physics
Instructor(ID, name, dept_name, office)
S
3
Course(code, dept_name, semester, enrolment)
Relational Databases Introduction
● Keys:
○ Need to make sure we can uniquely identify a tuple
within a relation
○ Superkey: a set of attributes that will uniquely identify a
tuple
○ Candidate key: Superkey with minimal set of attributes
○ Primary key: Candidate key that we (database
designers) choose as our unique ID
Relational Databases Introduction
● Keys:
○ Superkeys?
○ Candidate Keys?
○ Primary Key
Instructor
ID
name
dept_name office
12345 Harrington CMS
IC342
23456 Turing
CMS
IC123
41231 Einstein
Physics
SW999
23124 Mozart
Music
AA123
98765 Freud
Psychology SY234
Things to do this week:
● Readings: Course Syllabus
● Practice: None (1 bonus hour of self-care time)
● To-dos:
○ Check that you can log into Piazza
○ Check that you are enrolled in a tutorial
Next Week
● Tutorials start
● More on relational model
● Relational Algebra
○ (don’t worry, it’s not as scary as it sounds)
Brian Harrington
(Slides adapted from material by Dr. Purva Gawde and Dr Anna Bretscher)