Ch 3. Database systems, data centers, and business intelligence

database

database

is an organized collection of data

database management system (DBMS)

software that handles the storage, retrieval, and updating of data in a computer system

database administer (DBA)

skilled IS professional who directs all activities related to an organizations database

Hierarchy of data

1- Bit (binary digit): circuit that is either on/off 2- Byte: made up of 8 bits 3- Character: building block of info 4- Field : name/number/combo of characters that describes an aspect of a business object or activity 5- Record: collection of related data fields 6- File: collection of related data records 7- Database: collection of integrated and related files

entity

General class of people, places, or things (objects) for which data is collected, stored, and maintained

attribute

characteristic of an entity

data item

specific value of an attribute

key

field or set of fields in a record that is used to identify the record

key field

field or set of fields that uniquely identifies the record

data centre

Is a climate controlled building or set of buildings that house database servers and the systems that deliver mission-critical information and services -Traditional data centres: Consist of warehouses filled with row upon row of server racks and powerful cooling systems

Enterprise data modelling

investigates the general data and information needs of an organisation at the strategic level

Entity-relationship (ER) diagrams

data models that use basic graphical symbols to show the organization of and relationships between data

Relational Model

describes data using a standard tabular format, each row of a table represents a data entity (record), columns of the table represent attributes (fields)

domain

allowable values for data attributes

Manipulating data

Selecting: eliminates rows according to certain criteria Projecting: eliminates column in a table Joining: combines two or more tables Linking: manipulating two or more tables that share at least one common data attribute

Database Management Systems

Creating and implementing the right database system: (ensure that the database will support both business activities and goals)

data definition language (DDL)

collection of instructions and commands used to define and describe data and relationships in a specific database

data dictionary

detailed description of all data used in the database

concurrency control

method of dealing with a situation in which two or more users or applications need to access the same record at the same time

Data manipulation language (DML)

commands that manipulate the data in a database

Structured query language (SQL)

standard query language for relational databases

Database Administration / administrator(DBA)

Responsible for defining and implementing consistent principles for a variety of data issues

• works with users to decide the content of the database -Works with programmers as they build applications to ensure that their programs comply with database management system standards and conventions