Data base concept

2. 1. Planning: that is identifying information gap in an organization and
propose a database solution to solve the problem.
2. Analysis: Concentrates more on fact finding about the problem or the
opportunity.
 Feasibility analysis, requirement determination and
structuring, and selection of best design method are also
performed at this phase.
3. Design: in database designing more emphasis is given to this phase. The
phase is further divided into three sub-phases.
 Conceptual Design, Logical Design, Physical Design:
4. Implementation: the testing and deployment of the designed database
for use.
5. Operation and Support: administering and maintaining the operation
of the database system and providing support to users.

3.  is the process of coming up with different
kinds of specification for the data to be
stored in the database.
 is one of the middle phases we have in
information systems development
 Deals with describing how the data should be
perceived at different levels and finally how
it is going to be stored in a computer system.

4.  Sub-phases (Levels) of database design

5.  is the process of constructing a model of the
information used in an enterprise,
 independent of any physical considerations.
 is source of information for logical design
 Mostly uses ER Model to describe the data .
 refinement of the schema, which is
verification of Entities, Attributes, and
Relationships

6.  Conceptual design revolves around
discovering and analyzing organizational and
user data requirements
 The important activities are to identify
 Entities
 Attributes
 Relationships
 Constraints
 And based on these components develop the
ER model using
 ER diagrams

7.  Entity-Relationship modeling is used to
represent conceptual view of the database
 The main components of ER Modeling are:
 Entities
 Represented by Rectangle
 Attributes
 Represented by Oval
 Relationships
 Represented by Diamond
 Constraints
 Represent the constraint in the data

8.  is the process of constructing a model of the
information based on a specific data model,
 independent of DBMS and other physical
considerations.
 Normalization process
 Collection of Rules to be maintained
 Discover new entities in the process
 Revise attributes based on the rules and the
discovered Entities

9.  The first step before applying the rules in relational data
model is converting the conceptual design to a form
suitable for relational logical model, which is in a form of
tables.
 Converting ER Diagram to Relational Tables
 Three basic rules to convert ER into tables or relations:
 Rule 1: Entity Names will automatically be table names
 Rule 2: Mapping of attributes: attributes will be columns of
the respective tables.
 Atomic or single-valued or derived or stored attributes will be
columns
 Composite attributes: the parent attribute will be ignored and the
decomposed attributes (child attributes) will be columns of the
table.
 Multi-valued attributes: will be mapped to a new table where the
primary key of the main table will be posted for cross referencing.
 Rule 3: Relationships: relationship will be mapped by using a
foreign key attribute.
 Foreign key is a primary or candidate key of one relation used to
create association between tables.

10. Refinement: eliminates inconsistency,
ambiguity and redundancy.
 Identifies relations based on primary key
 Decompose relations with anomalies to produce
smaller, well-structured relations
1. Insertion Anomalies
2. Deletion Anomalies
3. Modification Anomalies

11.  Defines specific storage or access methods
used by database
 Tailored to a specific DBMS system –
 Includes estimate of storage space

12.  Physical design describes the base relation,
file organization, and indexes used to
achieve efficient access to the data, and any
associated integrity constraints and security
measures.
 Logical database design is concerned with
the what; physical database design is
concerned with the how.

14.  A good human computer interface
provides a unifying structure for finding,
viewing and invoking the different
components of a system.
 These are the means or methods by which
users interact with the system.
 Interface may be designed to allow:
 Command based interactions
 Menu based interaction
 Object based interaction: icons, symbols
 Natural language interaction

15.  Meaningful title
 Comprehensible instructions
 Logical grouping and sequencing of fields
 visually appealing layout of the form/report
 familiar field labels
 consistent terminology and abbreviation
 consistent use of color
 visible space and boundaries or data entry fields
 convenient cursor movement
 error correction for individual characters and entire
fields
 error massage for unacceptable fields
 optional field marked clearly
 explanatory massages for fields
 completion signal

17. 17
 The two fundamental concepts that need to be
considered while designing database systems are:
 Maintaining the consistency of the database to all the
changes, and
 Protecting the database from unauthorized users.

18. 18
 Integrity constraints ensure that the changes made
to the database by authorized users do not result in
a loss of data consistency.
 It is a predicate to the database that needs to be
declared at all time.
 Types of Constraints
 Key Constraints (Entity Integrity)
 Foreign Key Constraints (Referential Integrity)
 Domain Constraints (Domain Integrity)
 General Constraints (User Defined Integrity)

19. 19
 A domain constraint is a predicate on an attribute A
of each tuple of a relation to be atomic value from
a domain set domain(A).
 Syntax:
CREATE DOMAIN <domain_name> <data_type>
CONSTRAINT <constraint_name> CHECK <constraint>
 The CHECK statement can also be
 directly applied to a column without defining a domain,
 in a table definition as a tuple based constraint
CHECK (<logical_expression>)

20. 20
 Constraint for salary
CREATE DOMAIN BasicSalary NUMERIC(9, 2)
CONSTRAINT SalaryRange CHECK (VALUE>=150.00 AND
VALUE<=6000.00)
Salary NUMERIC(9, 2) CHECK (Salary>=150.00 AND
Salary<=6000.00)
 Domain Constraint
CREATE TABLE Employees (
:
CONSTRAINT EmpDate_Constraint CHECK (EmpDate <= GETDATE())
)

21. 21
 User defined constraint is an assertion defined by
the user requirement.
 Domain and Referential integrity constraints.
 The syntax for general assertion is:
CREATE ASSERTION <assertion_name> CHECK <predicate>
Example
CREATE ASSERTION NumberOfTeamMembers CHECK (8 >=
ALL (SELECT EmpId FROM EmpTeams GROUP BY TeamId)

22. 22
 Triggers are statements that the database
management system executes automatically in
response to a modification to the database.
Triggers need to specify:
 The event that will cause or initiate the trigger
execution,
 Condition to be specified for the trigger execution to
proceed, and
 The action to be taken in response.
action
condition
event
?




 


23. 23
 The trigger events are:
 INSERT, DELETE, UPDATE and SELECT.
 The actions for the triggers may be taken:
 After successful completion of the operation (event): AFTER
 Before the execution of the operation (event): BEFORE (INSTEAD OF)
 Syntax
CREATE TRIGGER <trigger_name>
ON {<table>|<view>}
{FOR | AFTER | INSTEAD OF} {[INSERT] | [UPDATE] | [DELETE] |
[SELECT]}
AS
<SQL_Statement>

24. 24
 Create a trigger that inserts the employee id to the
fulltime employee table if the employee is a
fulltime employee otherwise in the part-time
employee table
CREATE TRIGGER EmployeeType
ON [Employees]
AFTER INSERT
AS
If (SELECT empType From inserted) = 1
INSERT INTO [fulltimeEmployees] (empId)
SELECT empId FROM inserted
ELSE
INSERT INTO [parttimeEmployees] (empId)
SELECT empId FROM inserted

25. 25
 Database security refers to protection of the database from malicious
access such as:
 Unauthorized reading of data,
 Unauthorized modification of data, and
 Unauthorized destruction of data.
 Some of the threats to the database because of malicious access are:
 Loss of integrity,
 Loss of availability,
 Loss of confidentiality
 Security measure levels
 Database System,
 Operating System,
 Network,
 Physical,
 Human

26. 26
 Database system security can be implemented with
the use of:
 Account and Role Creation,
 Privilege granting,
 Privilege revocation, and
 Security level assignment

27. 27
 Authorization levels in a database system can be
set at broad categories as:
 Data Level Authorization
 Read
 Insert
 Update
 Delete
 Schema Level Authorization
 Index
 Resource
 Alter
 Drop

28. 28
 The syntax for privilege granting is as follows:
GRANT <privilege_list> ON {<table>|<view>}
TO <account_list> [WITH GRANT OPTION]
 <privilege_list> is possible data level authorization for
the table or view stated as:
{SELECT | INSERT | UPDATE | DELETE | ALL}
 To grant access to a specific column in a table:
GRANT REFERENCES (<column>) ON {<table>|<view>}
TO <account_list> [WITH GRANT OPTION]

29. 29
 The syntax for privilege revoking is as follows:
REVOKE <privilege_list> ON {<table>|<view>}
FROM <account_list> [RESTRICT | CASCADE]
 To revoke grant option from an account:
REVOKE GRANT OPTION FOR <privilege_list> ON
{<table>|<view>}
FROM <account_list>

30. 30
 The syntax to deny a privilege from an account list
is:
DENY <privilege_list> ON {<table>|<view>}
TO <account_list> [CASCADE]

31. 31
 Terminologies
 Plain text
 Cipher text
 Key
 Encryption
 Decryption
 
P
K
C
encryption
P 



 

 
P
K
C
decryption
P 



 


32. 32
 Cryptography:
 rendering plain information unintelligible, and
 restoring the encrypted information to intelligible form
 Symmetric Key Algorithms
 DES (Data Encryption Standard)
 IDEA (International Data Encryption Algorithm)
 Asymmetric Key Algorithms
 RSA (Rivest, Shamir and Adleman)
 DSA (Digital Signature Algorithm )
 Cryptanalysis : Breaking cipher

33. 33
 Authentication is a process of verifying the
identity of a user who is claimed to be.
 There are two ways of authenticating a user:
 Use of Password.
 User Account
 Password
 Challenge Response
 Challenge generated by the server
 Encrypted by the user with the private key of the user
 Decrypted by the server with the public key of the user