Transcript การเขียนโปรแกรมและการประ

Introduction to ECE613
Lecturer
AJ. Suwan Janin
Phone: 089-148-3993
E-mail: [email protected]
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Introduction
Database Fundamentals
Database Management System (DBMS)
Prevalent Database Models
History of Databases
Why Focus on Relational?
Conclusion
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Why the real world used database?
 Today databases are a part of the information
technology (IT) industry and business.
Banking transactions, travel reservations,
employment relationships, web site searches,
purchases, and most other transactions
 Data are recorded in and served by databases.
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Properties of a Database
A database is a collection of interrelated data items that
are managed as a single unit.
 Microsoft Access places the entire database in
a single data file.
 Oracle Corporation defines their database as a
collection of physical files managed their database
software product.
 Microsoft SQL Server and Sybase define a
database as a collection of data items common
owner,
Multiple databases managed by single instance of the
database management software.
A database object is a named data structure that is stored in a
database. The specific types of database objects supported in a
database vary from vendor to vendor and from one database
model to another.
Database model refers to the way in which a database organizes
its data to pattern the real world. The most common database
models are presented in “Prevalent Database Models”.
A file is a collection of related records that are stored as a single
unit by an operating system. Given the unfortunately similar
definitions of files and databases.
A number of Unix operating system vendors call their password file
a “database” .
Understanding of certain characteristics or properties that
databases possess that ordinary files do not, including the
following:
• Management by a Database Management System (DBMS)
• Layers of data abstraction
• Physical data independence
• Logical data independence
 The Database Management System (DBMS) is software
provided by the database vendor.
 Software products Microsoft Access, Oracle, Microsoft
SQL Server, Sybase, DB2, INGRES.
The DBMS provides all the basic services required to organize and
maintain the database, including the following:
• Moving data to and from the physical data files as needed.
• Managing concurrent data access by multiple users, including
provisions to prevent simultaneous updates from conflicting with
one another.
• Managing transactions so that each transaction’s database
changes are an all-or-nothing unit of work. In other words, if the
transaction succeeds, all database changes made by it are recorded
in the database; if the transaction fails, none of the changes it
made are recorded in the database.
• Support for a query language, which is a system of commands
that a database user employs to retrieve data from the database.
• Provisions for backing up the database and recovering from
failures.
• Security mechanisms to prevent unauthorized data access and
modification.
Figure 1-1 Database layers of abstraction
 Flat Files
Figure 1-2 Flat file
order system
Space exploration projects led to many significant developments in the
science and technology industries, including information technology.
As part of the NASA Apollo moon project, North American Aviation
(NAA) built a hierarchical file system named Generalized Update
Access Method (GUAM)in 1964.
IBM joined NAA to develop GUAM into the first commercially available
hierarchical model database, called Information Management System
(IMS), released in 1966.
• Definition, maintenance, and manipulation of data storage
structures is easy.
• Data is retrieved through simple ad hoc queries.
• Data is well protected.
• Well-established ANSI (American National Standards
Institute) and ISO (International Organization for
Standardization) standards exist.
• There are many vendors from which to choose.
• Conversion between vendor implementations is relatively
easy.
• RDBMSs are mature and stable products.
 This chapter introduces fundamental concepts .
 Definitions of the databases, properties common
to databases,
 Prevalent database models, a brief history of
databases.
 The rationale for focusing on the relational model.
THANK YOU FOR
YOUR KIND ATTENTION !!!
Lecturer
AJ. Suwan Janin