Chapter 4 Database Management Systems Chapter 4 What

Chapter 4 Database Management Systems Chapter 4

What is a Database Management System (DBMS)? § Database • An organized collection of related data § Database Management System • Comprises programs to store, retrieve, and otherwise manage a computerized database and to provide interfaces to application programs and to nonprogramming users Chapter 4 2

Functions of A Database Management System § Storing and Retrieving Data • The database sees the physical view of the data v. How the data are compressed and formatted, which data are stored near each other, and which indexes are created to simplify and speed finding data on the storage medium Chapter 4 3

Functions Database Management Functions ofof. AADatabase Management System § Storing and Retrieving Data • The database presents a logical view to the user and programmer v. Organizes and presents data elements in ways that managers and other users find helpful Chapter 4 4

Functions Database Management Functions ofof. AADatabase Management System § Managing Metadata • Metadata are data about data in the database • Example v. The fact that a company's invoice numbers are six digits long, with the first digit being either a 1 or 3 Chapter 4 5

Functions Database Management Functions ofof. AADatabase Management System § Limiting and Controlling Redundant Data in Multiple Systems • Companies often collect and store the same data in two or more different information systems Chapter 4 6

Functions Database Management Functions ofof. AADatabase Management System § Supporting Simultaneous Data Sharing • Concurrency control v. Describes the proper management of simultaneous attempts to update a database by multiple users or multiple software programs Chapter 4 7

Functions Database Management Functions ofof. AADatabase Management System § Providing Transaction Atomicity • The concept that a transaction cannot be split into smaller parts • If systems fails in midst of transaction, system is restored as if the entire transaction completed or no part of it completed Chapter 4 8

Functions Database Management Functions ofof. AADatabase Management System § Providing Backup and Recovery Services • Databases cannot be backed up like files because they are too large and in constant use • Backup techniques include v. Operating in parallel on two storage devices v. Use of temporary database during backup Chapter 4 9

Functions of A Database Management System § Providing Authorization and Security Services • Most DBMSs can limit who has access to specific data • DBMS can create limited views of data so that users can see only what they are authorized to see Chapter 4 10

Functions of A Database Management System § Enforcing Business Rules • A DBMS enforces rules that ensure related data are logically consistent Chapter 4 11

Database Applications § Support for Application Software • Providing a common data repository • Performing support functions, such as data storage, metadata storage, concurrency control, and other DBMS functions that would otherwise have to be performed by the application software Chapter 4 12

Database Applications § Data Warehouse • An enterprise-wide database designed to support business intelligence and management decision making rather than operational needs Chapter 4 13

Database Applications § Data Mart • Provides summary and historical data for business intelligence and decision making for a single department or division rather than an entire organization Chapter 4 14

Database Applications § Serving Dynamic Web Pages • Allows Web content managers to change Web pages by updating a database • Content management v. Software designed to ease the development of Web pages by fields from a database into a Web page template Chapter 4 15

Developing Databases through Data Design § Data Design • The process of identifying and formalizing the relationships among the elements of data that will form an organization's database Chapter 4 16

Developing Databases through Data Design [Insert Figure 4 -4 here] Chapter 4 17

Developing Databases through Data Design § Entity-Relationship (E/R) Model • The E/R model offers a pictorial way of showing the interrelationships among various types of data Chapter 4 18

The Entity. Relationship Model Figure 4 -5 Chapter 4 19

Technological Underpinnings § Distribution Architecture • Refers to how the organization distributes data and database processing physically among the computers in a network Chapter 4 20

Technological Underpinnings § Types of Distribution Architectures • Decentralized architecture v. Involves no data sharing • Centralized architecture v. Has a single DBMS running on a single computer and maintaining data centrally Chapter 4 21

Technological Underpinnings § Types of Distribution Architectures • Client/Server architecture v. Divides the functions of a DBMS among connected computers on a network, while centralizing permanent storage for all data on a computer called the database server Chapter 4 22

Technological Underpinnings § Types of Distribution Architectures • Distributed architecture v. Distributes both data and processing v. Treats data as a single database, giving every database client and every server access to all the data in the database no matter where it resides • Mixed architecture v. Utilizes more than one architecture Chapter 4 23

Technological Underpinnings § Database Models • Relational model v. A table represents a file with rows called tuples and columns called attributes Chapter 4 24

Technological Underpinnings [Insert Figure 4 -8 here] Chapter 4 25

Technological Underpinnings § Database Models • Object model v. Derives from object-oriented programming v. Object-oriented DBMSs store objects and object-class metadata Chapter 4 26

Technological Underpinnings § Database Models • XML model v. A language used to mark and identify components of Web-based transaction documents Chapter 4 27

Technological Underpinnings § Database Models • Network model v. Builds a tighter linkage between elements of data • Hierarchical model v. A precursor to the network model, as a network model with additional restrictions v. Views data as organized in a logical hierarchy Chapter 4 28

Managing the Data Resource § Data Administrator • Concerned with integrity of data, data redundancy, access controls, and rules about data relationships § Database Administrator (DBA) • Oversees functioning of particular DBMS • More technical than data administrator Chapter 4 29

End of Chapter 4 Database Management Systems Chapter 4