Database Concepts

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Chapter 1
Database Concepts
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Database Concepts

• Data is a meaningless static value. e.g. Ali,
  3421. What does 3421 means?
• Information is the data you process in a manner
  that makes it meaningful. Information can be
  provided only if proper data exists. e.g. Ali ID
  number is 0987.
• A database (DB) is a collection of a logically
  related persistent data, designed to meet the
  information needs of an organization. Can be
  generated maintained manually or automatically.
  
• Data is what you store in database.
• Information is what you retrieve from a database.

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Database Concepts

• A database application is a collection of data
  and the programs that allow the manipulation of
  these data to meet the information needs of an
  enterprise.
• Database Management System (DBMS) A software
  system that facilitates the creation and
  maintenance of a database, i.e. implementing
  database application.
• Application Program (of a Database) a computer
  program that interacts with database by issuing
  an appropriate request (SQL statement) to the
  DBMS.
• Database System (DBS) is database and Software
  (DBMS Application Program).
• ( Database (DB) DBMS Application
  Program ? Database System (DBS) )

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DBS Environment
Users/Programmers
DBS
Application Programs
DBMS
Query Process
Data Access
Database
Meta-Data
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Examples of Database Applications

• Edugate and ERegister.
• KSU Library.
• Supermarket system.
• Credit card system.
• Saudi Airlines Reservations.

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Other databases you may use
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File-Based Systems (FBS)

• FBS is a collection of application programs that
  perform tasks (e.g. reports) where each program
  defines and manages its own data.

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File-Based Systems (FBS
Orders Department Accounting Department
Payroll Department
Program A
Program B
Program C
Program A
Program B
Program A
Program B
Order Filing System
Invoicing System
Payroll System
Customer Master File
Inventory Master File
Back Order File
Inventory Pricing File
Customer Master File
Employee Master File
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File-Based Systems (FBS)

• Major limitations of FBS
• Data redundancy (Duplication of data)
• Different systems/programs have separate copies
  of the same data.
• Limited data sharing
• No centralized control of data.
• Lengthy development times
• Programmers must design their own file formats.
• Excessive Program maintenance
• 80 of information systems budget.

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Database Systems (DBS)

• DBS is a single large repository of data, defined
  once and managed using DBMS while used by many
  application programs.

DBS
Data Entry Reports
User 1 (Sales)
Sales Application Program
DBMS
Data Entry Reports
Database
User 2 (HR)
HR Application Program
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Database Systems (DBS)

• Major characteristics of DBS
• Self-describing nature of a database system.
• Program-data independence.
• Data Abstraction.
• Sharing of data and multi-user transactions
  processing (guarantee Concurrency Control).
• Support of multiple views of the data.

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Database Systems (DBS)

• Disadvantages of DBS
• Complexity.
• Size.
• Cost (DBMS, Hardware, Staff, Training).
• Performance.
• Higher impact of a failure.

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Database Management System (DBMS)

• A DBMS is a collection of software that
  facilitates the implementation and management of
  database applications.
• DBMS facilitates the following
• Create and Define a DB.
• Construct and Load a DB contents.
• Manipulate a DB (query update the DB).
• Control access to data.

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Database Management System (DBMS)

• Major Relational DBMS vendors/products
• Paradox/Corel.
• dBase/Clipper.
• FoxPro, Access SQL Server/MS.
• MySQL.
• DB2/IBM.
• Oracle, Sybase, Informix.

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DBMS Languages

• Data Definition Language (DDL)
• DDL is a descriptive language for defining and
  constructing the database.
• Allows users to specify the data types and
  structures and the constraints on the data to be
  stored in the DB.
• DDL compiler generates the meta-data that is
  stored in the data dictionary.

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DBMS Languages

• Data Manipulation Language (DML)
• DML is a language for retrieving and updating
  (insert, delete, modify) the data in the DB.
• Types of DML
• Low level or Procedural Language user
  specifies what data is required and how to get
  those data.
• High level or Nonprocedural Language user
  specifies what data is required without
  specifying how to get those data.

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DBMS Languages

• DBMS have a facility for embedding DDL DML
  (sub-languages) in a High-Level Language (COBOL,
  C, C or Java), which in this case is considered
  a host language.

C,C,Lisp,..
Application Program
DBMS
Call to DB
Local Vars (memory)
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Roles in the Database Environment
Communicate
User Requirement
Procedure
Write
Write
DB Designer
System Analyst
Application programmer
Design
DBA
Manage
Program
DBMS
App Program
Use
Naïve End User
DB
Use
H/W
Sophisticated End User
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Roles in the Database Environment

• System Analyst Determine the user requirements
  and develop the system specifications.
• Database Designer Identify the data and choose
  the appropriate structure to represent and store
  the data.
• Application Programmer Implement the application
  program based on the system specification.
• Database administrator (DBA) Administrates the
  DB, DBMS and related software.

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Roles in the Database Environment

• Database End-users They use the data for
  queries, reports and some of them update the
  database content (data). End-users can be
  categorized into
• Naïve users Invokes one of the permanent
  application programs that have been written
  previously.
• Sophisticated users form requests in a database
  query language.
• Additional Roles
• DBMS designer and implementer.
• Tool Developer.
• Operators and maintenance Personnel.