1. The Relational Model
May Aldoayan

2. Simple
uses the concept of a mathematical relation
Oracle
SQLServer and Acces
the SQL query language, which is the standard for commercial relational DBMSs.

3. The relational model represents the database as a collection of relations. Informally, each relation resembles a table of values or, to some extent, a flat file of records
May Aldoayan

4. Relational Data structure
Attributes
Branch
Figure 3.1
postcode
City
Street
branchNo
SW1 AEH
London
22 Deer Rd
B005
AB2 3SU
Aberdeen
16 Argyll St
B007
G11 9QX
Glasgow
163 Main St
B003
BS99 1NZ
Bristol
32 Manse Rd
B004
NW10 6EU
56 Clover Dr
B002
Relation
Cardinality
Degree
Foreign Key
Primary Key
Staff
branchNo
Salary
DOB
Sex
Position
LName
fName
StaffNo
B005
30000
1-Oct-45 M
Manager
White
John
SL21
B003
12000
10-Nov-60 F
Assistant
Beech
Ann
SG37
18000
24-Mar-58
Supervisor
Ford
David
SG14
B007
9000
19-Feb-70
Howe
Mary
SA9
24000
3-Jun-40
Brand
Susan
SG5
13-Jun-63
Lee
Julie
SL41
Relation
May Aldoayan

5. Relational Data structure
Relation: A relation is a table with columns and rows.
In the relational model, relations are used to hold information about the object to be represented in the database.
Attribute: An attribute is a named column of a relation.
Attribute can appear in any order and the relation will still be the same relation, and therefore convey the same meaning
May Aldoayan

6. Relational Data structure
Domain : A domain is the set of allowable values for one or more attributes.
Domains may be distinct for each attribute, or two or more attributes may be defined on the same domain.
Tuple: A tuple is a row of a relation.
The elements of a relation are the rows or tuples in the table.
May Aldoayan

7. Examples of Attribute Domains
Pearson Education © 2009

8. Relational Data structure
Degree: The degree of a relation is the number of attributes it contains.
In figure 3.1, The Branch relation has four attributes or degree four. This means that each row of the table is a four-tuple, containing four values.
A relation with only one attribute would have degree one and be called unary relation or one-tuple.
A relation with two attribute is called binary, one with three attribute is called ternary
May Aldoayan

9. Relational Data structure
Cardinality: The cardinality of a relation is the number of tuples it contain.
Relational database: A collection of normalized relation with distinct relation name .
Database relations:
Relation schema: A named relation defined by a set of attribute and domain name pairs.
Relational database schema: A set of relation schema, each with a distinct name.
If R1, R2, .., Rn are a set of relation schemas, then relational schema R is:
R= {R1, R2, .., Rn}
May Aldoayan

10. Alternative Terminology for Relational Model
Pearson Education © 2009

11. Properties of relations
The relation has a name that is distinct from all other relation names in the relational schema.
Each cell of the relation contains exactly single value
Each attribute has a distinct name
The values of an attribute are all of the same domain
Each tuple is distinct. There are no duplicate tuples
The order of attributes has no significance
the order of tuples has no significance; theoretically
May Aldoayan

12. Relational Keys
Primary Key: The candidate key that is selected to identify tuples uniquely within the relation.
Foreign Key : is an attribute, or set of attributes, within one relation that matches the CK of some relation. Used to represent relationship between tuples of two relations.
May Aldoayan

13. Integrity Constraints
Null
Represents value for an attribute that is currently unknown or not applicable for tuple.
Deals with incomplete or exceptional data.
Represents the absence of a value and is not the same as zero or spaces, which are values.
Pearson Education © 2009

14. Relation Schema Student
Dept
GPA
DOB
LName
FName
StudentNo
D001
4.03
Alsaleh
Maha
3.90
AlAhmed
Reem
D002
3.50
AlQahtani
Sara
4.50
Alotaibi
Suha
D003
4.89
AlMutairi
Lamea
STUDENT (StudentNo, Lname, Fname, DOB, GPA, Dept)
Department
Location
Name Department
DeptNo
Build# 1
Computer Science
D001
Build# 3
Business Administrator
Doo2
Build # 6
Science
D003
DEPARTMENT (DeptNo, Department Name, Location)
May Aldoayan

15. 1:1 Relationship  Relational Model
Identify an entity type (S) (preferably total participator)
Include the PK of the other entity (T) as a FK in S
Add attributes that describes the relationship.
EMPLOYEE(EmpNo, Lname, Fname, DOB)
BRANCH(BrnNo, Name, EmpNo)
LName
FName
Name
EmpNo
DOB
BrnNo 1 1
manage
EMPLOYEE
BRANCH
(0,1)
(1,1)
May Aldoayan

16. 1:M Relationship  Relational Model
Identify a participating entity type (S) on the m-side
Include the PK of the other entity type (T) as a FK in S
if S is at “M-side” of relationship type then include primary key of T in S
Add attributes that describes the relationship
STAFF (StaffNo, Lname, Fname, DOB)
PropertForRent(ProertyNo, Address, StaffNo)
LName
FName
Address
PropertyNo
StafNo
Name
DOB 1 M
Oversees
Staff
ProperyForRent
(0,*)
(1,1)
May Aldoayan

17. M:N Relationship  Relational Model
Create a new relation R to represent the relationship
Include the PK of participating entity types (T & S) as FK in R. The combination of the two FK will form the PK of R
Add attributes that describes the relationship
EMPLOYEE(StaffNo, Lname, Fname, DOB)
Project(ProjNo, Name)
Work-on(EmpNo, ProjNo , hours)
LName
Name
ProjNo
Fname
hours
EmpNo
DOB M N
Work-on
Employee
Peoject
May Aldoayan

18. n-ary Relationship  Relational Model
Create a new relation R to represent the relationship
Include the PK of the participating entities as FK in R. The combination of all FK form the PK of R.
Add attributes that describes the relationship
BUSINESS(BizNo) LAWYER(LawNo) SUPPLIER(SupNo)
contract(BizNo, SupNo, LawNo, StartDate, EndDate)
StartD
EndD
SupNo
BizNo
contract
BUSINESS
SUPPLIER
Lawyer
LawNo
May Aldoayan

19. Composite Attribute Relational Model
Include its simple components in the relation
EMPLOYEE(EmpNo, Fname, initial, Lname, DOB)
initial
FName
LName
name
DOB
emp_no
EMPLOYEE
May Aldoayan

20. Multi Valued Attribute Relational Model
Suppose A is a relation that contains the multi valued attribute
Create a relation R to represent the attribute
Include the PK of A as FK in R
The PK of R is the combination of the PK of A (FK) & the multivalued attribute
EMPLOYEE(EmpNo, DOB)
TELEPHONE(EmpNo, tel_no)
DOB
EmpNo
Tel_no
EMPLOYEE
May Aldoayan

21. EER Relational Model Mandatory/NonDisjoint
Suppose specialization with subclasses (S1, S2, .., Sm} & a superclass C
Create a relation L to represent C with PK & attributes
Include the unshared attributes for each subclass Si, 1 i  m
Add discriminator to distinguish the type of each tuple
May Aldoayan

22. EER Relational Model Mandatory/NonDisjoint
EMPLOYEE(EmpNo, Fname, Lname, DOB,Salary,TypingSpeed,TGrade,
EngType, Secretary Flag, Technician Flag, Engineer Flag)
Salary
EmpNo
LName
EMPLOYEE
Fname
DOB o
Typing
Speed
EngType
SECRETARY
TECHNICIAN
ENGINEER
TGrade
May Aldoayan

23. EER Relational Model Mandatory/Disjoint
Suppose specialization with subclasses (S1, S2, .., Sm} & a superclass C.
Create a relation Li, 1 i  m, to represent each combination of super/subclass
May Aldoayan

24. EER Relational Model Mandatory/Disjoint
SECRETARY(EmpNo, Fname, Lname, DOB, Salary,TypingSpeed) TECHNICIAN(EmpNo, Fname, Lname, DOB, Salary,Tgrade) ENGINEER(EmpNo, Fname, Lname, DOB, Salary, EngType)
Salary
EmpNo
LName
EMPLOYEE
Fname
DOB d
Typing
Speed
EngType
SECRETARY
TECHNICIAN
ENGINEER
TGrade
May Aldoayan

25. EER Relational Model Optional/NonDisjoint
Suppose specialization with subclasses (S1, S2, .., Sm} & a superclass C
Create a relation L to represent C with PK & attributes
Create a relation Li to represent each subclass Si, 1 i  m
May Aldoayan

26. EER Relational Model Optional/NonDisjoint
EMPLOYEE(EmpNo, Fname, Lname, DOB, Salary) SUB-EMP(EmpNo, TypingSpeed,TGrade, EngType, Secretary Flag, Technician Flag, Engineer Flag)
Salary
EmpNo
LName
EMPLOYEE
Fname
DOB o
Typing
Speed
EngType
SECRETARY
TECHNICIAN
ENGINEER
TGrade
May Aldoayan

27. EER Relational Model Optional/Disjoint
Suppose specialization with subclasses (S1, S2, .., Sm} & a superclass C
Create a relation L1 to represent C with PK & attributes
Create a relation L2 to represent all subclasses Si, 1 i  m
Add discriminator to distinguish the type of each tuple
May Aldoayan

28. EER Relational Model Optional/Disjoint
EMPLOYEE(EmpNo, Fname, Lname, DOB, Salary)
SECRETARY(EmpNo, TypingSpeed)
TECHNICIAN(EmpNo, Tgrade)
ENGINEER(EmoNo, EngType)
Salary
EmpNo
LName
EMPLOYEE
Fname
DOB d
Typing
Speed
EngType
SECRETARY
TECHNICIAN
ENGINEER
TGrade
May Aldoayan

29. E/R  Relational Model Relational Model E/R Model Relational
Entity Type
FK or relation
1:1 or 1:M Relationship Type
Relation & 2 FK
M:N Relationship Type
Relation & n FK
n-ary Relationship Type
Attribute
Simple attribute
Simple component attribute
Composite attribute
Relation and FK
Multivalued attribute
Domain
Value set PK
Key attribute
May Aldoayan

30. Integrity Constraints
General Constraints
Additional rules specified by users or database administrators that define or constrain some aspect of the enterprise.
Pearson Education © 2009

31. Integrity Constraints
Entity Integrity
In a base relation, no attribute of a primary key can be null.
Referential Integrity
If foreign key exists in a relation, either foreign key value must match a candidate key value of some tuple in its home relation or foreign key value must be wholly null.
Pearson Education © 2009

32. Entity Integrity
The first integrity rule applies to the primary Keys of base relations.
Entity integrity :
In a base relation, no attribute of a primary key can be null
May Aldoayan

33. Relational Integrity The second integrity rule applies to foreign key.
Referential Integrity: If a foreign key exists in a relation, either the foreign key value must match a candidate key value of some tuple in its home relation or the foreign key value must be wholly null.
Enterprise constraints: Additional rules specified by the users or DBA of the DB.
based on the ways an organization perceives and uses its data
(e.g. number of staff working in a branch is at most 20)
May Aldoayan

34. Views
Base relation is a named relation corresponding to an entity in the conceptual schema, whose tuples are physically stored in the DB
View is a derived relation. Virtual, may not exist, but dynamically derived from one or more base relations.
The only information about a view that is stored in the database is its structure.
The external model can consist of both conceptual level relations (base relations) and derived views.
May Aldoayan

35. Views STUDENT Base Relation STUDENT_GPA View Dept GPA DOB LName FName
StudentNo
D001
4.03
Alsaleh
Maha
3.90
AlAhmed
Reem
D002
3.50
AlQahtani
Sara
4.50
Alotaibi
Suha
D003
4.89
AlMutairi
Lamea
Base
Relation
STUDENT_GPA
GPA
StudentNo
4.03
3.90
3.50
4.50
4.89
View
May Aldoayan

36. Purpose of Views
It provides a powerful and flexible security mechanism by hiding parts of the DB from certain users.
It permits users to access data in a way that is customized to their needs, so that the same data can be seen by different users in different ways, at the same time.
It can simplify complex operations. It allow you to work with data from different tables simultaneously.
Supports logical data independence
May Aldoayan

37. Updating Views
All updates to a base relation should be immediately reflected in all views that reference that base relation.
All updates to a view should be reflected in the underlying base relation, under the following rules:
Updates are allowed through a view defined using a simple query involving a single base relation & containing either the PK or a CK of the base relation
Update are NOT allowed through views involving multiple base relations
Updates are not allowed through views involving aggregation or grouping operations
May Aldoayan