IT214 - Chapter 1 notes
IT214 - Chapter 1 notes IT214
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This 4 page Class Notes was uploaded by Andrew Sudwi on Tuesday September 15, 2015. The Class Notes belongs to IT214 at George Mason University taught by Dr. Ioulia Rytikova in Fall 2015. Since its upload, it has received 39 views. For similar materials see Database Fundamentals in Information technology at George Mason University.
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Date Created: 09/15/15
Chapter 1 Databases specialized structures that allow computer based systems to store manage and retrieve data quickly Data raw facts not processed It is the building blocks of information Information processed data with meaning to reveal meaning it requires context Knowledge the body of information and facts about a speci c subject Data management discipline that focuses on the proper generation storage and retrieval of data Database a shared integrated computer structure that stores a collection of 1 Enduser data raw facts of interest to the end user 2 Metadata data about data through which the end user data are integrated and managed It provides a description of the data characteristics and the set of relationships that links the data Database management system DBMS a collection of programs that manages the database structure and controls access to the data stored in the database Advantages of having a DBMS between end user s application and the database 1 DBMS enables the data in the database to be shared among multiple applications or users 2 DBMS integrates the many different users views of the data into a single allencompassing data repository Advantages of having a DMBS Improved data sharing Improved data security Better data integration Minimized data inconsistency Data inconsistency exists when different versions of the same data appear in different places 5 Improved data access Query is a speci c request issued to the DBMS for data manipulation ad hoc query is a spur of the moment question The DBMS sends an answer back called query result set to the application 6 Improved decision making Data quality is a comprehensive approach to promoting the accuracy validity and timelines of the data DBMS does NOT guarantee data quality it provides a framework to facilitate data quality initiatives 7 Increased end user productivity Database can classi ed according to PWF 1 Number of user A singleuser database supports only one user at a time A singleuser that runs on a personal computer is called a desktop database A multiuser database supports multiple users at the same time Workgroup database supports less than 50 Enterprise database supports more than 50 usually hundreds 2 Database locations Centralized database supports data located a single site Distributed database supports data across several sites 3 Expected type and extent of use Operational database supports a company39s day to day operations also known as transactional or production database Data warehouse focuses primarily on storing data used to generate information required to make tactical or strategic decisions Unstructured data data that exist in their original raw state in the format in which they were collected Structured data taking unstructured data and formatting such data to facilitate storage use and the generation of information Semistructured data data that have already been processed to some extent Extensible Markup Language XML a special language used to represent and manipulate data elements in a textual format XML database supports storage and management of semistructured XML data 0 Database design refers to the activities that focus on the design of the database structure that will be used to store and manage enduser data 0 Basic le terminology 1 Data raw facts telephone number date of birth customer name sales value They have no meaning unless they are organized 2 Field a character of group of character alpha or numeric that has a speci c meaning A eld is used to de ne and store data columns 3 Record a logically connected set of one or more elds that describe a person place or thing rows 4 File a collection of related records 0 Challenges associated with le systems 1 2 3 Lengthy development times Older le systems required extensive programming for data retrieval Dif culty of getting quick answers Ad hoc queries were impossible due to the programming procedure Complex system admin More les means more management programs need to be created Lack of security and limited data sharing Extensive programming Any change to a le structure requires modi cations in all of the programs which means more error and more time spent on debugging Structural dependence access to a le is dependent on its structure le system Structural independence changes are possible without affecting the application program39s ability to access data Data dependence when data access programs are subject to change when any data type is changed Data independence when it is possible to make changes in the data storage characteristics without affecting the application program39s ability to access data Island of information scattered data locations Data redundancy the same data are stored unnecessarily at different places Uncontrolled data redundancy sets the stage for 1 Poor data security 2 Data inconsistency 3 Data anomaly Happens when not all of the required changes in the redundant data are made successfully Update anomalies Insertion anomalies Deletion anomalies Database system an organization of components that de ne and regulate the collection storage management and use of data within a database environment There 5 major parts to a database system 1 Hardware 2 Software 3 types of software are needed a Operating system software manages all hardware components and make it possible for all other software to run on the computers Windows Linux MAC OS Unix b The database within the database system SQL Oracle IBM s DBZ c Application program and utility software application programs are used to access data found within the database to generate reports to facilitate decision making Utilities are the software tools used to help manage the database system39s computer components 3 People There 5 types of users based speci c job functions a System admin oversee the database system39s general operations b Database admin DBA manage the DBMS and ensure that the database function properly Database designers System analyst and programmers they design and implement the application program e End users an 4 Procedures instructions and rules that govern the design and use of the database system 5 Data the collection of facts stored in the database DBMS function 1 Pquot39gt Data dictionary management The DBMS stores de nitions of the data elements and their relationships metadata in a data dictionary DBMS uses the data dictionary to look up the required data component structures and relationships thus relieving you from having to code such complex relationships in each program Additionally any changes made in a database structure are automatically recorded in the data dictionary freeing you from having to modify all of the programs that access the changed structure Data storage management it is important for performance tuning allows the database to perform more efficiently Data transformation and presentation the DBMS transforms entered data to conform to required data structure Date is entered as mdy in the US but the format will conform to dmy for a user in the UK Security management Multiuser access control Backup and recovery management Data integrity management Database access languages and application programming interfaces Query language a nonprocedural language one that lets the user specify what must be done without having to specify how it is to be done Structured query language SQL the de facto query language and data access standard supported by the majority of DBMS vendos Database communication interfaces
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