Akram Jalal
Ahlia University
MIS
College of Business and Finance
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COURSE IDENTIFICATION

LECTURES: M 16:30 – 18:10 - Class 6.

Lab: W 16:30 – 18:10 - Lab 1.

INSTRUCTOR: Dr. Akram Jalal

Office:

Email: akarim@ahlia.edu.bh

Phone:

Office Hours: Tuesdays, 10am to 11:30am
Walk-ins are welcome any time based on availability
Dr. Akram Jalal
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ASSIGNMENTS:
 Submissions will be in class. Late submissions will be
penalized by at the rate of 10% per day. Assignments
later than three days will not be accepted.


Assignment should be written using computer tool.
Hand writing home works are not accepted.
All students should achieve their own work according
to the Ahlia University rules, which means you must
write up your favourite solution independently.
Exams:
 The midterm exam will be given in-class on ----.
This exam will covers material and chapters (1, 2 and
5).
 The date of final exam is based on the final exam
timetable.
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GRADING:
Attendance: 10%
Assignment: 20%,
Midterm: 30%,
Final: 40%.
Consistent class attendance is required absences will seriously
affect your total grade.
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
by Raghu Ramakrishnan &
Johannes Gehrke
◦ 3rd edition


Available: Next week in the
library
The readings of this book are
required, even if material is
not covered in the lectures.
All other readings are
optional.
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Course Structure (Outline)
Week
Hours
1
Lecture
3
Lab
---
2
3
---
ILOs
Topics
Teaching Method
Assessment Method
A1
Course Introduction & Familiarisation
LecturesClass discussions
Oral Participation
A1, A2,
B1, B2,
B3, C3,
D2, D4
A1, B2, B3, C1,
C3
Introductions to DBMS
LecturesClass discussions
Oral Participation
/Group
discussions
LecturesClass discussionsLab Exercises
LecturesClass discussionsLab Exercises
LecturesClass discussionsLab Exercises
Oral Participation
/Group
discussions
Oral Participation
/Group
discussions
Oral Participation
/Group
Assignment
All topics weeks 2-5.
--
Midterm Exam
Structured Query Language (SQL)
1.
Basic SQL query
LecturesClass discussionsLab Exercises
LecturesClass discussionsLab Exercises
LecturesClass discussionsLab Exercises
LecturesClass discussionsLab Exercises
LecturesClass discussions
Oral Participation
/Group
Assignment
Oral Participation
/Group
Assignment
Oral Participation
/Group
Assignment
Oral Participation
/Group
Assignment
Oral Participation
/Group
Discussions
Oral Participation
/Group
discussions
Oral Participation
/Group
discussions
3
1,1/2
1,1/2
4
1,1/2
1,1/2
A1, B2, B3, C1,
C3
Database design
5
1,1/2
-
A1, A3, B3, D3
Structured Query Language (SQL)
1.
Basic SQL query
5
1,1/2
-
6
1,1/2
1,1/2
B1, C1, C3, D4,
D3
A1, A3, B3, D3
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1,1/2
1,1/2
A1, A3, B3, D3
8
1,1/2
1,1/2
Database design
1.
Structured Query Language (SQL)
Union Intersection and Exception
1.
Structured Query Language (SQL)
Union Intersection and Exception
A1, A3, B3, D3
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1,1/2
1,1/2
A1, A3, B3, D3
Structured Query Language (SQL)
1.
Aggregate operators
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3
-
A1, A3, B2, B3,
C1, C3
Tree Structured Indexing
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3
-
A1, A3, B2, B3,
C1, C3
Tree Structured Indexing
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3
-
A2, A3,
B1, B3,
D2, D4
Submitting assignment 1
Transaction Management
LecturesClass discussions
LecturesClass discussions


A large, integrated collection of data, typically
describing the activities of one or more
organizations.
Models a real-world enterprise, e.g. a university
database might contain information about:
Entities such as:
◦

◦





students, courses, instructors,
Relationships
One to One
One to Many
Many to Many
A Database Management System (DBMS) is a
software designed to assist in maintaining and
utilizing large collection of data.
DBMS also needed to store the data in files and
write application-specific code to manage it.
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
Data independence.
DBMS provides an abstract view of the data that hides data representation
and storage.
When the DBMS hides certain details of how data is stored and maintained, it
provides what is called as the abstract view of data. Complexity (of data and
data structure) is hidden from users through several levels of abstraction.
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Efficient data access.
DBMS utilizes a variety of sophisticated techniques to store and retrieve
data efficiently.
Data integrity and security.
If data is always accessed through DBMS, the DBMS can enforce integrity
constrains.
E.g.1. Before inserting salary, DBMS should check that department budget
is not exceeded. E.g.2 access control.
Uniform data administration.
When several users share the data, centralizing the administration of data
can offer the significant improvement.
Concurrent access, recovery from crashes.
DBMS schedules concurrent access to the data in such a manner that users
can think of the data as being accessed by only one user at a time.
Reduced application development time:
DBMS supports important functions that are common to many applications
accessing data in DBMS
1. Large data sets (100s of GBs, or TBs, …)

No indices
◦ Finding “George” in huge flat file is expensive

Modifications intractable without better data
structures
◦ “George”  “Georgie” is very expensive
◦ Deletions are very expensive
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4. Security?
◦
◦
File system may lack security features
File system security may be rough
5. Application programming interface (API)?
 Interfaces, interoperability
6. How to query the data?
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
A data model is a collection of high level data description
constructs. Most of DBMS today are based on relational data
model.
Semantic data model (such as E-R diagram) is more abstract, high
level data model and served as starting point and subsequently
translated into a database design.
E-R diagram allows us to periodically denote entities and the
relationships among them.

A schema is a description of a particular collection of data, using
the a given data model.

e.g. Student (Sid: string, Name: String, age: Integer)

The relational data model is the most widely used model today
(which is used in numerous systems such as Oracle, DB2, MS
Access) is based on relation (which described as a set of records) ,
basically a table with rows and columns.
◦
◦
Every relation has a schema, which describes the fields (columns, or
attributes).
Other data models are: Hierarchical model, the network model, objectoriented model and object-relational model.
Each external schema consists of
one or more relations and view

External
schema –
View1
Data in DBMS is described at
three levels of abstractions.
Many External echemas,
single conceptual (logical)
Conceptual Schema
schema and physical schema.
◦ Views describe how users see the
Physical Schema
data.
User 1

External
schema –
view 2
User 2
User 3
External
schema view3
User 4
(one per each DB)
(one per each DB)
◦
Conceptual schema defines logical
structure. In RDBMS CS describes all
relations that are stored in the
database.
Student(sid: string, Name: String, age: Integer)
Faculty ( …..
◦
Physical schema describes the files
and indexes used. It summarizes
how the relations described in the
conceptual schema are actually
stored on secondary storage
devices such as disks and tapes.
External schema allow data access
to be customized (and authorized).
DDL (data definition Language) used
to define external and conceptual
schemas). Concerned with the way
individual users see the data.
Information about those schemas are
stored in system catalogs.

Start with SQL DDL to create tables:
CREATE TABLE Students (
Name CHAR(30)
SSN CHAR(9) PRIMARY KEY NOT NULL,
Category CHAR(20)
);

Continue with SQL to populate tables:
INSERT INTO Students
VALUES('Hillary', '123456789', 'undergraduate');
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Takes:
Students:
SSN
123-45-6789
234-56-7890
Courses:
CID
C20.0046
C20.0056

Name
Hillary
Barak
…
Category
undergrad
grad
…
SSN
123-45-6789
CID
C20.0046
123-45-6789
C20.0056
234-56-7890
C20.0046
…
CName
Databases
Advanced Software
semester
Spring,
2004
Spring,
2004
Fall, 2003
Ultimately files, but complex
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
Find all the students who have taken C20.0046:
SELECT SSN FROM Takes
WHERE CID='C20.0046';

Find all the students who have taken C20.0046
previously:
SELECT SSN FROM Takes
WHERE CID='C20.0046' AND
Semester='Fall, 2005';

Find the students’ names:
SELECT Name FROM Students, Takes
WHERE Students.SSN=Takes.SSN AND
CID='C20.0046' AND Semester='Fall, 2005';
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
Conceptual Schema:
◦ Students(ssn: string, name: string, login: string, age:
int, gpa: real)
◦ Courses(cid: string, cname: string, credits: int)
◦ Enrolled(sid:string, cid:string, grade: string)

Physical schema:
◦ Relations stored as unordered text files.
◦ Indices on first column of each relation

Views:
◦ My_courses(cname: string, grade: string, credits: int)
◦ Course_info(ssn: string, name: string, status: string)
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failover/rovery
concurrent use
deal with large datasets?
security
interop?
querying in what?
 DBMS as application
Q: How does a DBMS solve these problems?
A: See third part of course, but for now…
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


Consider a database that holds information about
airline reservations. At any time, it is possible that
several travel agents are looking up information
about available seats on various flights and making
new seat reservations.
When several users access a database concurrently,
the DBMS must order their requests to avoid
conflicts.
ACID test properties
◦ Atomicity
 all or nothing
◦ Consistency
 constraints on relationships
◦ Isolation
 concurrency control
 simulated solipsism
◦ Durability
 Crash recovery
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

Key concept is transaction, which is an atomic
sequence of database actions (reads/writes).
Each transaction, executed completely, must
leave the DB in a consistent state if DB is
consistent when the transaction begins.


Avoiding inconsistent state
A DBMS prevents this outcome
◦ Xacts are all or nothing

One simple idea: log progress of and plans
for each xact
◦ Durability: changes stay made (with log…)
◦ Atomicity: entire xact is committed at once
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
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Many users  concurrent execution
◦ Disk access is slow (compared to CPU)
◦  don’t waste CPU – keep running
Interweaving actions of different user programs
 but can lead to inconsistency:
◦ e.g., two programs simultaneously withdraw from the
same account
For each user, should look like a single-user
system
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
Each xact (on a consistent DB) must leave it in
a consistent state
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
Concurrent execution of user programs
is essential for good DBMS performance.
◦


Because disk accesses are frequent, and relatively slow,
it is important to keep the cpu humming by working on
several user programs concurrently.
Interleaving actions of different user programs
can lead to inconsistency: e.g., check is cleared
while account balance is being computed.
DBMS ensures such problems don’t arise: users
can pretend they are using a single-user
system.

Database design:
◦ Entity/Relationship models
◦ Modeling constraints

The relational model:
◦ Relational algebra
◦ Transforming E/R models to relational schemas

SQL
◦ DDL & query language
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
Why would you choose a database system instead of simply
storing data in operating system files? When would it make sense
not to use a database system?
Explain the difference between external, internal, and conceptual
schemas. How are these different schema layers related to the
concepts of logical and physical data independence?
 Which of the following plays an important role in representing
information about the real world in a database? Explain each of
briefly.
1. The data definition language (DDL).
2. The data manipulation language (DML).
3. The buffer manager.
4. The data model (DM).

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