Database Management:
Revision B4 Final
Hoda Mohamed Waguih
Database Management – Hoda M. Waguih
2009/2010
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Basic Concepts
• What is Data, Metadata, Information?
• What is Database?
• What is file-based systems?
• Characteristics of file-based systems.
• Disadvantages of file-based approach.
Database Management – Hoda M. Waguih
2009/2010
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Basic Concepts
• What is a DBMS.
• Typical functions of a DBMS.
• Major components of the DBMS environment.
• Advantages & disadvantages of DBMSs.
Database Management – Hoda M. Waguih
2009/2010
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Basic Concepts
• What is a data dependence?
• Problems are caused by data redundancy?
• What is a View & View Benefits?
• What is Concurrency control system.
• What is a Constraint in a database?
Database Management – Hoda M. Waguih
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Basic Concepts
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What is a Model?
What is a Relation?
Characteristics of a Relation
What is an Attribute?
What is a Domain of an Attribute?
What is a Key? Types of Keys?
Integrity Constrains
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Basic Concepts
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What is Entity integrity constrain?
What is Referential integrity constrain?
General constrain
Null Values
Difference between a base table and a view
Functional Dependency
Database Management – Hoda M. Waguih
2009/2010
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Basic Concepts
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Conceptual Model
What is an Entity, Attribute, Relationship
Strong Entity & Weak Entity
Entity with physical existence
Entity with conceptual existence
Entity Types & Entity Sets
Relationship Types & Relationship Sets
Different Types of attributes
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Basic Concepts
• Degree of a relationship type
• Uniqueness constraint
• Participation constraint
• Participation constraint & Existence Dependency
• ER Diagrams & Naming Conventions
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Basic Concepts
• ER-to-Relational Mapping Algorithm
• Mapping Binary Relationship
⁃ Foreign key approach
⁃ Merged relationship approach
⁃ Cross reference or relationship relation approach
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Basic Concepts
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Skipped
Superclass/subclass
Super type/sub type
Class/subclass relationship
Type inheritance
Specialization / Generalization
Attribute-defined specialization
User defined Specialization
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Basic Concepts
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Skipped
Specialization /generalization lattices
Specialization /generalization hierarchies
Multiple inheritance / Single inheritance
Specialization /generalization constraint
– Disjointness constraint
– Completeness constraint
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Basic Concepts
• Data Anomalies
– Deletion anomalies
– Update anomalies
– Insertion anomalies
Database Management – Hoda M. Waguih
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Basic Concepts
• First normal form (1NF)
• Second normal form (2NF)
• Third normal form (3NF)
Database Management – Hoda M. Waguih
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The Relational Algebra Operations
• Operations from Mathematical Set Theory
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UNION,
INTERSECTION,
SET DIFFERENCE, and
CARTESIAN PRODUCT
• Operations specifically for Relational
Database
– SELECT,
– PROJECT, and
– JOIN
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Sample Review Questions
• Define the following terms:
Data, meta-data, information, database, DBMS,
database system, database catalog,
Program-data independence, user view, DBA,
end user, transaction, deductive database system,
Data model, database schema, database state,
internal schema, conceptual schema, external
schema, data independence, DDL, DML, query
language
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2009/2010
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Sample Review Questions
• Discuss the main characteristics of the database
approach and how it differs from traditional file
systems.
• Discuss the capabilities that should be provided
by a DBMS.
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Sample Review Questions
• What is the difference between a database schema
and a database state?
• What is the difference between logical data
independence and physical data independence?
• What is an candidate Key? What is primary Key?
• What is an entity type? What is an entity set?
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Sample Review Questions
• Explain the differences among an entity, an entity
type, and an entity set.
• What is a relationship type? Explain the differences
among a relationship instance, a relationship type, and
a relationship set.
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Sample MCQ
• One disadvantage of file processing systems is:
A) reduced data duplication.
B) program-data independence.
C) limited data sharing.
D) enforcement of integrity constraints.
• Which of the following is a characteristic of the database
approach?
A) It stresses the integration of data.
B) It duplicates data.
C) It creates physical relationships.
D) It reduces storage.
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Sample MCQ
• A user view is:
a) what a user sees when he or she looks out the window.
b) a table or set of tables.
c) a logical description of some portion of the database.
d) a procedure stored on the server.
• In a file processing environment, descriptions for data and the
logic for accessing the data is built into:
a)application programs.
b)database descriptors.
c)fields.
d)records.
Database Management – Hoda M. Waguih
2009/2010
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Sample MCQ
• The logical representation of an organization’s data is called a(n):
A)
B)
C)
D)
database model.
entity-relationship model.
relationship systems design.
database entity diagram.
• A relationship between the instances of a single entity type is
called a(n) _____ relationship.
A)
B)
C)
D)
ternary
primary
binary
unary
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Sample MCQ
• Which of the following is a generic entity type that has a
relationship with one or more subtypes?
A)
B)
C)
D)
Megatype
Supertype
Subgroup
Class
• The property by which subtype entities possess the values of all
attributes of a supertype is called:
A) hierarchy reception.
B) class management.
C) attribute inheritance.
D) generalization.
Database Management – Hoda M. Waguih
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Sample MCQ
• The ______ rule states that an entity instance can
simultaneously be a member of two (or more) subtypes.
A. disjoint
B. overlap
C. partial specialization
D. total specialization
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• In a supertype/subtype hierarchy, each subtype has:
A. only one supertype.
B. many supertypes.
C. at most two supertypes.
D. at least one subtype.
•Database Management – Hoda M. Waguih
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Sample (True/False)
• With the traditional file processing approach, each
application shares data files, thus enabling much data
sharing.
• The database approach emphasizes integration and
sharing of data throughout the organization.
• Metadata are data that describe the properties of other
data.
• Redundancy increases the risk of inconsistent data.
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Sample (True/False)
• An entity instance of a subtype represents the same
entity instance of the supertype.
• A member of a subtype does NOT necessarily have to
be a member of the supertype.
• Specialization is the reverse of generalization.
• A completeness constraint may specify that each
entity of the supertype must be a member of some
subtype in the relationship.
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Sample (True/False)
• The E-R model is used to construct a conceptual
model.
• An entity is a person, place, object, event, or concept
in the user environment about which the organization
wishes to maintain data.
• A single occurrence of an entity is called an entity
instance.
• The relationship among the instances of three entity
types is called a unary relationship
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Sample: Fill in the space
• Databases are an organized collection of ______ data.
• Facts, text, graphic images, sound, and video segments that
have meaning in the user’s new environment are called
_____________.
• __________ is data that has been processed in such a way as
to increase the knowledge of the person who uses the data.
• __________ is data that describes the properties or
characteristics of other data.
• In the beginning of computer-based data processing, _______
were used instead of databases.
• Unplanned and uncontrolled _________________ can often
lead to a loss of metadata integrity.
Database Management – Hoda M. Waguih
2009/2010
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Sample: Fill in the space
• A logical representation of the data for an organization or for a
business area is
• A person, place, object, event, or concept about which the
organization wants or needs to store data is called a(n) _____.
• An attribute whose value can be calculated from a related
attribute is called a(n) _____ attribute.
Database Management – Hoda M. Waguih
2009/2010
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Database Management – Hoda M. Waguih
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Sample Exercise
Answer:
(a) Each SECTION record is related to a COURSE record.
(b) Each GRADE_REPORT record is related to one STUDENT
record and one SECTION record.
(c) Each PREREQUISITE record relates two COURSE records:
one in the role of a course and the other in the role of a
prerequisite to that course.
Database Management – Hoda M. Waguih
2009/2010
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Sample Exercise
1.12 Cite some examples of integrity constraints that you think can
apply to the database shown in Figure 1.2.
Answer:
1. The Student_number should be unique for each STUDENT record .
2. The Course_number should be unique for each COURSE record
(1,2 key constraint).
3. A value of Course_number in a SECTION record must also exist in
some COURSE record (referential integrity constraint).
4. A value of Student_number in a GRADE_REPORT record must
also exist in some STUDENT record (referential integrity constraint).
5. The value of Grade in a GRADE_REPORT record must be one of
the values in the set {A, B, C, D, F, I, U, S} (domain constraint).
6. Every record in COURSE must have a value for Course_number
(entity integrity constraint).
Database Management – Hoda M. Waguih
2009/2010
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Sample Exercise
• Specify all the relationships among the records of the
database shown in Figure 1.2.
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Sample Exercise
Consider the following set of requirements for a UNIVERSITY
database that is used to keep track of students’ transcripts:
− The university keeps track of each student’s name, student
number, Social Security number, current address and phone
number, permanent address and phone number, birth date, sex,
class (freshman, sophomore, ..., graduate), major department, minor
department (if any), and degree program (B.A., B.S., ..., Ph.D.).
Some user applications need to refer to the city, state, and ZIP Code
of the student’s permanent address and to the student’s last name.
Both Social Security number and student number have unique
values for each student.
− Each department is described by a name, department code,
office number, office phone number, and college. Both name
and code have unique values for each department.
Database Management – Hoda M. Waguih
2009/2010
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Sample Exercise
− Each course has a course name, description, course number, number of
semester hours, level, and offering department. The value of the course
number is unique for each course.
− Each section has an instructor, semester, year, course, and section
number. The section number distinguishes sections of the same course
that are taught during the same semester/year; its values are 1, 2, 3, ..., up
to the number of sections taught during each semester.
− A grade report has a student, section, letter grade, and numeric grade (0,
1, 2, 3, or 4).
Design an ER schema for this application, and draw an ER diagram
for the schema. Specify key attributes of each entity type, and
structural constraints on each relationship type. Note any
unspecified requirements, and make appropriate assumptions to
make the specification complete.
Database Management – Hoda M. Waguih
2009/2010
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Sample Exercise
7.19 - Consider the ER diagram of Figure 7.20,
which shows a simplified schema for an airline
reservations system. Extract from the ER diagram
the requirements and constraints that resulted in
this schema. Try to be as precise as possible in your
requirements and constraints specification.
Database Management – Hoda M. Waguih
2009/2010
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Answer
(1) The database represents each AIRPORT, keeping its unique
AirportCode, the AIRPORT Name, and the City and State in
which the AIRPORT is located.
(2) Each airline FLIGHT has a unique number, the Airline for the
FLIGHT, and the Weekdays on which the FLIGHT is scheduled
(for example, every day of the week except Sunday can be coded
as X7).
(3) A FLIGHT is composed of one or more FLIGHT LEGs (for
example, flight number CO1223 from New York to Los Angeles
may have two FLIGHT LEGs: leg 1 from New York to Houston
and leg 2 from Houston to Los Angeles). Each FLIGHT LEG has
a DEPARTURE AIRPORT and Scheduled Departure Time, and
an ARRIVAL AIRPORT and Scheduled Arrival Time.
Database Management – Hoda M. Waguih
2009/2010
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Answer
(4) A LEG INSTANCE is an instance of a FLIGHT LEG on a specific Date
(for example, CO1223 leg 1 on July 30, 1989). The actual Departure and
Arrival AIRPORTs and Times are recorded for each flight leg after the flight
leg has been concluded. The Number of available seats and the AIRPLANE
used in the LEG INSTANCE are also kept.
(5) The customer RESERVATIONs on each LEG INSTANCE include the
Customer Name, Phone, and Seat Number(s) for each reservation.
(6) Information on AIRPLANEs and AIRPLANE TYPEs are also kept. For
each AIRPLANE TYPE (for example, DC-10), the TypeName, manufacturing
Company, and Maximum Number of Seats are kept. The AIRPORTs in which
planes of this type CAN LAND are kept in the database. For each
AIRPLANE, the AirplaneId, Total number of seats, and TYPE are kept.
Database Management – Hoda M. Waguih
2009/2010
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Sample Exercise
• 7.23 - Consider the ER diagram shown in Figure 7.21 for part of
a BANK database. Each bank can have multiple branches,
and each branch can have multiple accounts and loans.
• (a) List the strong (non weak) entity types in the ER diagram.
• (b) Is there a weak entity type? If so, give its name, its partial
key, and its identifying relationship.
• (c) What constraints do the partial key and the identifying
relationship of the weak entity type specify in this diagram?
Database Management – Hoda M. Waguih
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Sample Exercise
(d) List the names of all relationship types, and specify the
(min, max) constraint on each participation of an entity
type in a relationship type. Justify your choices
(e) List concisely the user requirements that led to this ER
schema design.
(f) Suppose that every customer must have at least one
account but is restricted to at most two loans at a time, and
that a bank branch cannot have more than 1000 loans.
How does this show up on the (min,max) constraints?
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Answer
(a) Entity types: BANK, ACCOUNT, CUSTOMER, LOAN
(b) Weak entity type: BANK-BRANCH. Partial key: BranchNo.
Identifying relationship: BRANCHES.
(c) The partial key BranchNo in BANK-BRANCH specifies that
the same BranchNo value ay occur under different BANKs. The
identifying relationship BRANCHES specifies that BranchNo
values are uniquely assigned for those BANK-BRANCH entities
that are related to the same BANK entity. Hence, the combination
of BANK Code and BranchNo together constitute a full identifier
for a BANK-BRANCH.
(d) Relationship Types: BRANCHES, ACCTS, LOANS, A-C, L-C.
The (min, max) constraints are shown below.
Database Management – Hoda M. Waguih
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Answer
(e) The requirements may be stated as follows: Each BANK has a
unique Code, as well as a Name and Address. Each BANK is related
to one or more BANK-BRANCHes, and the BranhNo is unique
among each set of BANK-BRANCHes that are related to the same
BANK.
Each BANK-BRANCH has an Address. Each BANK-BRANCH has
zero or more LOANS and zero or more ACCTS. Each ACCOUNT
has an AcctNo (unique), Balance, and Type and is related to exactly
one BANK-BRANCH and to at least one CUSTOMER. Each LOAN
has a LoanNo (unique), Amount, and Type and is related to exactly
one BANK-BRANCH and to at least one CUSTOMER. Each
CUSTOMER has an SSN (unique), Name, Phone, and Address, and
is related to zero or more ACCOUNTs and to zero or more LOANs.
Database Management – Hoda M. Waguih
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Answer
• (f) The (min, max) constraints would be changed as
follows:
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