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Unit 8: Database System

2. To provide isolation between programs accessing a database concurrently. Without isolation Notes
the program’s outcomes are possibly erroneous.
A database transaction, by definition, must be atomic, consistent, isolated and durable. Database
practitioners often refer to these properties of database transactions using the acronym ACID.
Transactions provide an “all-or-nothing” proposition, stating that each work-unit performed in
a database must either complete in its entirety or have no effect whatsoever. Further, the system
must isolate each transaction from other transactions, results must conform to existing constraints
in the database, and transactions that complete successfully must get written to durable storage.

8.5 Common Corporate DBMS

Additional types of software applications have been used in the past and may be still in use
on older, legacy systems at various organizations around the world. However, these examples
provide an overview of the most popular and most-widely used by IT departments. Some typical
examples of DBMS include: Oracle, DB2, Microsoft Access, Microsoft SQL Server, PostgreSQL,
MySQL, and FileMaker.

8.5.1 ORACLE

The Oracle Database (commonly referred to as Oracle RDBMS or simply as Oracle) is an
object-relational database management system (ORDBMS) produced and marketed by Oracle
Corporation.
Larry Ellison and his friends and former co-workers Bob Miner and Ed Oates started the
consultancy Software Development Laboratories (SDL) in 1977. SDL developed the original
version of the Oracle software. The name Oracle comes from the code-name of a CIA-funded
project Ellison had worked on while previously employed by Ampex.

8.5.2 DB2

The IBM DB2 Enterprise Server Edition is a relational model database server developed by IBM.
It primarily runs on UNIX (namely AIX), Linux, IBM i (formerly OS/400), z/OS and Windows
servers. DB2 also powers the different IBM InfoSphere Warehouse editions. Alongside DB2 is
another RDBMS: Informix, which was acquired by IBM in 2001.

8.5.3 Microsoft Access

Microsoft Office Access, previously known as Microsoft Access, is a relational database
management system from Microsoft that combines the relational Microsoft Jet Database Engine
with a graphical user interface and software-development tools. It is a member of the Microsoft
Office suite of applications, included in the Professional and higher editions or sold separately. In
mid-May 2010, the current version of Microsoft Access 2010 was released by Microsoft in Office
2010; Microsoft Office Access 2007 was the prior version.
Access stores data in its own format based on the Access Jet Database Engine. It can also import
or link directly to data stored in other applications and databases.

Software developers and data architects can use Microsoft Access to develop application software,
and “power users” can use it to build simple applications. Like other Office applications, Access
is supported by Visual Basic for Applications, an object-oriented programming language that can
reference a variety of objects including DAO (Data Access Objects), ActiveX Data Objects, and
many other ActiveX components. Visual objects used in forms and reports expose their methods

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