Unit 2 – Application & Implication Module 1 – Information Management

Differentiate these Differentiate between these Terms used in Information Management üFields – a field is a unit of data consisting of one or more character ex Name, Tel#, Address üRecords – a collection of related fields ex Name, ID, Address üTables – a number of related records üRelation – a 2-dimentional table containing rows and columns of data üTuple – a column in a relation üAttribute – a row in a relation üNull values - the value given an attribute in a tuple – if the attribute is inapplicable or its value is unknown

Differentiate these Differentiate between these Terms used in Information Management üFiles – a file is collection of related records ex. Data on all students of 6th form IT class üDatabase – an integrated collection files üDatabase Management System – system software that facilitate the management of a database üRelational Database Schema – A listing showing relation names, attribute names, key attributes and foreign keys.

Differentiate these Differentiate between these Terms used in Information Management üKey – a minimal set of attributes that uniquely identifies each row in a relation üSuperkey- A set of attributes that uniquely identifies each row in a relation. ü Composite key- a key consisting of more than one attribute. üCandidate Key- Any set of attributes that could be chosen as a key of a relation. üPrimary Key – The candidate key designated for principal use in uniquely identifying rows in a relation. üForeign Key- A set of attributes in one relation that constitutes a key in some other (or possibly the same) relation; used to indicate logical links between relations.

The Hierarchy of Data ü Bit (a binary digit): a circuit that is either on or off ü Byte: eight bits ü Character: basic building block of information ä Each byte represents a character ä Can be an uppercase letter, lowercase letter, numeric digit, or special symbol ü Field: typically a name, number, or combination of characters that describes an aspect of a business object or activity ü Record: a collection of related data fields ü File: a collection of related records ü Database: a collection of integrated and related files ü Hierarchy of data: bits, characters, fields, records, files, and databases

The Hierarchy of Data

Data Entities, Attributes, and Keys üE ntity: a generalized class of people, places, or things (objects) for which data is collected, stored, and maintained ü Attribute: characteristic of an entity ü Data item: value of an attribute ü Key: field or set of fields in a record that is used to identify the record ü Primary key: field or set of fields that uniquely identifies the record

Data Entities, Attributes, and Keys

The Database Approach ü Traditional approach to database management: separate data files are created for each application ä Results in data redundancy (duplication) ä Data redundancy conflicts with data integrity ü Database approach to database management: pool of related data is shared by multiple applications ä Significant advantages over traditional approach

The Database Approach

Table 3.2: Disadvantages of the Database Approach

Data Modeling and the Relational Database Model ü When building a database, consider: ä Content: What data should be collected, at what cost? ä Access: What data should be provided to which users and when? ä Logical structure: How should data be arranged to make sense to a given user? ä Physical organization: Where should data be physically located?

Data Modeling üBuilding a database requires two types of designs äLogical design äAbstract model of how data should be structured and arranged to meet an organization’s information needs äPhysical design äFine-tunes the logical database design for performance and cost considerations

Data Modeling üData model: a diagram of data entities and their relationships üEntity-relationship (ER) diagrams: data models that use basic graphical symbols to show the organization of and relationships between data

The Relational Database Model ü Relational model: all data elements are placed in two- dimensional tables (relations), which are the logical equivalent of files ü In the relational model ä Each row of a table represents a data entity ä Columns of the table represent attributes ä Domain: the allowable values for data attributes

Manipulating Data

Database Management Systems (DBsMS) ü Interface between: ä Database and application programs ä Database and the user ü Creating and implementing the right database system ensures that the database will support both business activities and goals ü DBMS: a group of programs used as an interface between a database and application programs or a database and the user

Overview of Database Types üFlat file: A flat file database is a database which, when not being used, is stored on its host computer system as an ordinary, non-indexed "flat" file. To access the structure of the data and manipulate it, the file must be read in its entirety into the computer's memory. ü Single user : Only one person can use the database at a time ä Examples: Access, FileMaker & InfoPath ü Multiple user: ä Allows dozens or hundreds of people to access the same database system at the same time ä Examples: Oracle, Sybase, and IBM

Creating and Modifying the Database ü Data definition language (DDL) ä Collection of instructions/commands that define & describe data and data relationships in a database(db) ä Allows db creator to describe the data & the data relationships that are to be contained in the schema ü Data dictionary: a detailed description of all the data used in the database

Storing and Retrieving Data ü When an application requests data from the DBMS, the application follows a logical access path ü When the DBMS goes to a storage device to retrieve the requested data, it follows a path to the physical location (physical access path) where the data is stored

Manipulating Data & Generating Reports ü Query-By-Example (QBE): a visual approach to developing database queries or requests ü Data manipulation language (DML): commands that manipulate the data in a database ü Structured Query Language (SQL): ANSI standard query language for relational databases ü Database programs can produce reports, documents, and other outputs

Database Administration ü Database administrator (DBA): directs or performs all activities to maintain a database environment ä Designing, implementing, and maintaining the database system and the DBMS ä Establishing policies and procedures ä Employee training

Popular Database Management Systems ü Popular DBMSs for end users: Microsoft Access and FileMaker Pro ü Entire market includes databases by IBM, Oracle, and Microsoft ü Examples of open-source database systems: PostgreSQL and MySQL ü Many traditional database programs are now available on open-source operating systems

Selecting a DBMS ü Important characteristics of databases to consider ä Size of the database ä Cost of the system ä Number of concurrent users ä Performance ä Ability to be integrated with other systems ä Vendor considerations

Using Databases with Other Software ä Database management systems are often used with other software packages or the Internet ü A database management system can act as a front-end application or a back-end application ä Front-end application: interacts with users ä Back-end application: interacts with applications

Linking Databases to the Internet ü Linking databases to the Internet is important for many organizations and people ü Semantic Web ä Developing a seamless integration of traditional databases with the Internet ä Allows people to access and manipulate a number of traditional databases at the same time through the Internet

Business Intelligence üBusiness intelligence (BI): gathering the right information in a timely manner and usable form and analyzing it to have a positive impact on business äTurns data into useful information that is then distributed throughout an enterprise üCompetitive intelligence: aspect of business intelligence limited to information about competitors and the ways that knowledge affects strategy, tactics, and operations üCounterintelligence: steps an organization takes to protect information sought by “hostile” intelligence gatherers

Distributed Databases üDistributed database äData may be spread across several smaller databases connected via telecommunications devices äCorporations get more flexibility in how databases are organized and used üReplicated database äHolds a duplicate set of frequently used data

Object-Oriented and Object-Relational Database Management Systems üObject-oriented database äStores both data and its processing instructions äMethod: a procedure or action äMessage: a request to execute or run a method

Visual, Audio, and Other Database Systems üVisual databases for storing images üAudio databases for storing sound üVirtual database systems: allow different databases to work together as a unified database system üOther special-purpose database systems äSpatial data technology: stores and accesses data according to the locations it describes and permits spatial queries and analysis

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