data base systems study text
PAPER NO. CT 31
SECTION 3
CERTIFIED
INFORMATION COMMUNICATION
TECHNOLOGISTS
(CICT)
DATA BASE SYSTEMS
STUDY TEXT
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KASNEB SYLLABUS
GENERAL OBJECTIVE
This paper is intended to equip the candidate with the knowledge, skills and attitude that will enable
him/her to administer and manage databases
LEARNING OUTCOMES
A candidate who passes this paper should be able to:
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Write structured query language (SQL) statements to manipulate data in databases
Develop a database application
Handle transactions and concurrency controls
Administer databases
Integrate databases and other applications
Manage database integrity issues
CONTENT
1. Introduction to databases
 Files, records, files and databases
 History of database systems
 Traditional file systems versus the database approach
 Characteristics, importance and limitations of database systems
 Database components and architecture
2. File organisation techniques
 Storage structures and blocking
 Unordered files
 Sequential files
 Indexing
3. Database models
 The role of data modeling
 The hierarchical model
 The relational model
 The object-oriented model
 The object-relational model
4. Database development life cycle
 Data and user requirements specification
 Stages of database development
 Conceptual, logical and physical database design
 Writing database requirements specifications
5. Relational database model
 Relational database concepts and properties
 E-R database design
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Database design anomalies
Normalisation
Relational algebra
Creating database design
implementing database design in mysql /oracle /DB2
6. Structured query language (SQL)
 Data definition language
 Data manipulation language
 Structure of SQL statements
 Data control
 in-built functions
 Writing SQL statements
 Using SQL functions
7. Transaction management and concurrency control
 Transaction management
 Properties of a transaction
 Serialisability and concurrency control
 Lock-based and timestamp-based protocols
 Types of failures
 Database recovery concepts and mechanisms
8. Database administration
 Database users
 Data administration
 Functions and roles of database administrators
 Monitoring database performance
9. Database security and integrity
 Security and integrity concepts
 Social, ethical and legal database issues
 Threats to database security and integrity
 Managing threats
 Establishing data backup procedure
10. Distributed database systems
 Introduction of concepts
 Distribution methods - fragmentation and replication
 Concurrency control mechanisms in distributed systems
 Two-tier database architecture
 Three-tier database architecture
11. Data warehousing and data mining
 Overview of data warehousing
 Characteristics of a data warehouse
 Components of a data warehouse
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Types of data warehouses
Elements of a data warehouse
Over view of data mining
Techniques of data mining
12. Integrating databases to other applications
 Importance of integrating databases to other applications
 Integrating databases to other applications (visual basic.net, C++, Java, C# among others)
 Developing web enabled database applications
13. Emerging issues and trends
CHAPTER 1
INTRODUCTIONS TO DATABASES
Data hierarchy
Data Hierarchy refers to the systematic organization of data, often in a hierarchical form. Data
organization involves fields, records, files and so on.
A data field holds a single fact or attribute of an entity. Consider a date field, e.g. "September 19,
2004". This can be treated as a single date field (e.g. birthdate), or 3 fields, namely, month, day
of month and year.
A record is a collection of related fields. An Employee record may contain a name field(s),
address fields, birthdate field and so on.
A file is a collection of related records. If there are 100 employees, then each employee would
have a record (e.g. called Employee Personal Details record) and the collection of 100 such
records would constitute a file (in this case, called Employee Personal Details file).
Files are integrated into a database. This is done using a Database Management System. If there
are other facets of employee data that we wish to capture, then other files such as Employee
Training History file and Employee Work History file could be created as well.
History of Database Systems
Early Manual System
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Before-1950s
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Data was stored as paper records.
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Lot of man power involved.
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Lot of time was wasted e.g. when searching
Therefore inefficient
Revolution began
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1950s and early 1960s:
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Data processing using magnetic tapes for storage
Tapes provide only sequential access
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Punched cards for input
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Late 1960s and 1970s:
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Hard disks allow direct access to data
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Data stored in files
File based systems
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Adequate for small applications
Drawbacks
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Separation and isolation of data
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Each program maintains its own set of data.
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Users of one program may be unaware of potentially useful data held by other programs
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Duplication of data
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Same data is held by different locations.
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Wasted space and potentially different values and/or different formats for the same item.
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Data dependence
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File structure is defined in the program code.
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Incompatible file formats
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Programs are written in different languages, and so cannot easily access each other‘s
files.
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Fixed Queries/Proliferation of application programs
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Programs are written to satisfy particular functions.
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Any new requirement needs a new program.
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Database Approach
Arose because:
Definition of data was embedded in application programs, rather than being stored separately and
independently.
No control over access and manipulation of data beyond that imposed by application programs.
Result:
The database and Database Management System (DBMS).
Database Management Systems (DBMS)
Relational
Object-oriented Object-relational
XML
IMDB
Java
1960‘s Hierarchical Network
1970‘s
1990‘s
CMDB Mobile
Embedded
1995+
Hierarchical Model
Well suited for data which are in someway related Hierarchically begin with a strictly defined
tree of data nodes Each node can contain some identifying data, plus a set of subnodes of a
specific child type
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Network Model
 Supported more complex relations
 Physical file pointers were used tomodel the relations between files
 Relations had to be decide in advance
 Most suitable for large databases with well-defined queries and well-defined applications.
Relational Model (1970’s)
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E.F. Codd introduced the relational model in 1970
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Provides a conceptually simple model for data as relations (Typically considered
―tables) withal data visible.
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DB2 from IBM is the first DBMS product based on the relational model
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Other DBMS based on the relational model were developed in the late 1980s
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today, DB2, Oracle, and SQL Serve rare the most prominent commercial
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DBMS products based on the relational model
Object Oriented Data Model (1990’s)
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Goal of OODBMS is to store object-oriented programming objects in a database without
having to transform them into relational format.
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Extend the entity-relationship data model by including encapsulation, methods and
object identity
Object-relational models
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Extend the relational data model by including object orientation and constructs to deal
with added data types.
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Allow attributes of tuples to have complex types, including non-atomic values such as
nested relations.
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Preserve relational foundations, in particular the declarative access to data, while
extending modeling power.
Modern Database Management Systems
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DBMS are large complex pieces of software designed specifically for the efficient
management of data.
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Examples:
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Oracle (Oracle Corporation)
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Ingres (Computer Associates)
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SQL Server (Microsoft Corporation)
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Access (Microsoft Corporation)
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IMS, DB2 (IBM)
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And many more…s
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