database concepts -pgdm induction

Database Concepts

Lecture slides by - Prof. Archana Raje

Why Study Databases?Databases are useful Many computing applications deal with large amounts of Data Database systems give a set of tools for storing, searching and managing this data.

Databases in ITDatabases are a core topic in Information TechnologyBasic concepts and skills with database systems are part of the skill set you will be assumed to have as a IT user.*Lecture slides by - Prof. Archana Raje


Where are databases?You cannot avoid it and its everywhere!You can say it actually makes the current society and your life work!Banking/Credit card /Social Security InfoOnline shopping/booking*Lecture slides by - Prof. Archana Raje


*Lecture slides by - Prof. Archana Raje


Data vs. InformationData:Raw facts; building blocks of informationUnprocessed informationInformation:Data processed to reveal meaningAccurate, relevant, and timely information is key to good decision makingGood decision making is key to survival in global environment

Lecture slides by - Prof. Archana Raje*


Data in contextLecture slides by - Prof. Archana Raje*Context helps users understand data


Converting data to information Summarized dataLecture slides by - Prof. Archana Raje*Graphical displays turn data into useful information that managers can use for decision making and interpretation


Basic DefinitionsDatabase: A collection of related data.Data: Known facts that can be recorded and have an implicit meaning.Mini-world: Some part of the real world about which data is stored in a database. For example, student grades and transcripts at a university.Database Management System (DBMS): A software package/ system to facilitate the creation and maintenance of a computerized database.Database System: The DBMS software together with the data itself. Sometimes, the applications are also included.



DatabaseDatabaseshared, integrated computer structure that houses:End user data (raw facts)Metadata (data about data)Lecture slides by - Prof. Archana Raje*


Example of MetadataLecture slides by - Prof. Archana Raje*Descriptions of the properties or characteristics of the data, including data types, field sizes, allowable values, and data context


Database Systems A database system consists of Data (the database)Software Hardware Users Database systems allow users to Store Update Retrieve Organize Protect their data.



Database UsersEnd users Use the database system to achieve some goal Application developersWrite software to allow end users to interface with the database system Database Administrator (DBA)Designs & manages the database system Database systems programmer Writes the database software itself



Database Management SystemLecture slides by - Prof. Archana Raje*Performs functions that guarantee integrity and consistency of data

Data dictionary management Defines data elements and their relationships

Data storage management Stores data and related data entry forms, report definitions, etc.

Data transformation and presentation Translates logical requests into commands to physically locate and retrieve the requested data


Database Management SystemLecture slides by - Prof. Archana Raje*Performs functions that guarantee integrity and consistency of dataSecurity management Enforces user security and data privacy within databaseMulti-user access controlCreates structures that allow multiple users to access the dataBackup and recovery management Provides backup and data recovery procedures


The DBMS Manages the Interaction Between the End User and the Database*Lecture slides by - Prof. Archana Raje


Historical Development of Database TechnologyEarly Database Applications: The Hierarchical and Network Models were introduced in mid 1960s and dominated during the seventies. A bulk of the worldwide database processing still occurs using these models.Relational Model based Systems: The model that was originally introduced in 1970 was heavily researched and experimented with in IBM and the universities. Relational DBMS Products emerged in the 1980s.Lecture slides by - Prof. Archana Raje*


Historical Development of Database TechnologyObject-oriented applications: OODBMSs were introduced in late 1980s and early 1990s to cater to the need of complex data processing in CAD and other applications. Their use has not taken off much.Data on the Web and E-commerce Applications: Web contains data in HTML (Hypertext markup language) with links among pages. This has given rise to a new set of applications and E-commerce is using new standards like XML (eXtended Markup Language).Lecture slides by - Prof. Archana Raje*


Extending Database CapabilitiesNew functionality is being added to DBMSs in the following areas:Scientific ApplicationsImage Storage and ManagementAudio and Video data managementData MiningSpatial data managementTime Series and Historical Data ManagementThe above gives rise to new research and development in incorporating new data types, complex data structures, new operations and storage and indexing schemes in database systems. Lecture slides by - Prof. Archana Raje*


Tables and Their CharacteristicsTable: Two-dimensional structure composed of rows and columnsContains group of related entities an entity setTerms entity set and table are often used interchangeablyTable also called a relation because the relational models creator, Codd, used the term relation as a synonym for table



Example of a Relation*Lecture slides by - Prof. Archana Raje


Attribute TypesEach attribute of a relation has a nameThe set of allowed values for each attribute is called the domain of the attributeAttribute values are (normally) required to be atomicE.g. the value of an attribute can be an account number, but cannot be a set of account numbersThe special value null is a member of every domain*Lecture slides by - Prof. Archana Raje


Characteristics of a Relational TableTable 3.1*Lecture slides by - Prof. Archana Raje


Relational SchemaA Relational schema is a textual representation of the database tables where each table is described by its name followed by the list of its attributes in the parenthesis. The primary key attribute(s) are underlined. Schema diagram



KeysConsists of one or more attributes that determine other attributesPrimary key (PK) is an attribute (or a combination of attributes) that uniquely identifies any given entity (row)A multi-attribute key is known as Composite key.Any attribute that is part of a key is known as a key is known as a key attribute.*Lecture slides by - Prof. Archana Raje


KeysA Superkey is a set of one or more attributes that, taken collectively, allow us to identify uniquely a tuple in the relation.A Candidate Key can described as a superkey without redundancies, i.e. minimal superkeyPrimary key is the candidate key chosen to be the unique row identifier.Primary key is a superkey as well as a candidate key.



KeysForeign key (FK) An attribute whose values match primary key values in the related tableReferential integrity FK contains a value that refers to an existing valid tuple (row) in another relationSecondary key Key used strictly for data retrieval purposes*Lecture slides by - Prof. Archana Raje


Relational Database Keys*Lecture slides by - Prof. Archana Raje


Integrity Rules*Lecture slides by - Prof. Archana Raje


Microsoft AccessMicrosoft Access is a Relational Database Management System (RDBMS), Access is known as a desktop database system because it's functions are intended to be run from a single computer. In contrast to a server database application (such as SQL Server), where it is intended to be installed on a server, then accessed remotely from multiple client machines.Microsoft (or MS) Access is a software package that you install just like any other software package, and is bundled as part of the Microsoft Office suite.



Access Versus ExcelExcel may be fine if you've only got a small amount of data, and if you don't have many attributes against each piece of dataIt may be fine if you don't have much in the way of relational data across multiple worksheets. Once you start storing many attributes against each piece of data, and perhaps you find yourself repeating information across multiple worksheets, then it's time to start using Access Another important reason for using Access over Excel is, if you need to generate a lot of queries and reports.*Lecture slides by - Prof. Archana Raje


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