28.06.2013 Views

Papers in PDF format

Papers in PDF format

Papers in PDF format

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

3.1 Database Types<br />

There are different k<strong>in</strong>ds of database management systems (DBMS) available:<br />

• Network<br />

• Hierarchical<br />

• Relational<br />

• Object oriented<br />

• Text based<br />

Network and hierarchical database management systems are still hold<strong>in</strong>g the most data stored<br />

<strong>in</strong> databases. However <strong>in</strong> the context of image databases and WWW they can be ignored anyway.<br />

There are many more terms conta<strong>in</strong><strong>in</strong>g database, for example deductive databases, active<br />

databases, scientific databases, real-time databases, time databases, etc. These do not refer to a<br />

DBMS itself, but to special features required for specific applications, which usually are implemented<br />

us<strong>in</strong>g relational or object oriented technology.<br />

3.1.1 Relational DBMS<br />

Relational database management systems (RDBMS) could be called state of the art look<strong>in</strong>g at<br />

the usage numbers, the standardization of query languages and available products. The idea for<br />

RDBMS was born <strong>in</strong> 1970 with the relational model by E.F. Codd. „A relational database allows<br />

the def<strong>in</strong>ition of data structures, storage and retrieval operations, and <strong>in</strong>tegrity constra<strong>in</strong>ts.<br />

In such a database, the data and relations between them are organized <strong>in</strong> tables. A<br />

table is a collection of records and each record <strong>in</strong> a table conta<strong>in</strong>s the same fields. Certa<strong>in</strong> fields<br />

may be designated as keys, which means that searches for specific values of that field will use<br />

<strong>in</strong>dex<strong>in</strong>g to speed them up. Records <strong>in</strong> different tables may be l<strong>in</strong>ked if they have the same<br />

value <strong>in</strong> one particular field <strong>in</strong> each table.“ [15] RDBMS have been designed for bus<strong>in</strong>ess applications<br />

like account<strong>in</strong>g. The idea was to hold the data separate from the application program<br />

<strong>in</strong> a reliable manner. They are flexible and well known and provide the standardized Structured<br />

Query Language (SQL) for access to the data. RDBMS are not very well able to deal with<br />

multimedia objects and very complex structures. L<strong>in</strong>ks between objects are only possible us<strong>in</strong>g<br />

the equality of keys. Multimedia data types are usually only supported with b<strong>in</strong>ary large objects<br />

(BLOBs) and hardly any functions.<br />

3.1.2 Object Oriented DBMS<br />

Object oriented database management systems (OODBMS) have hardly any market share today<br />

(1%

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!