Chapter 6

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Information Technology Management
ITM 102
Vikraman Baskaran

Chapter 6: Database and Information Management 6.1 - Organizing Data in Traditional File Environment Problems with the Traditional File Environment - data redundancy - data inconsistency, - program-data dependence: the coupling of data stored in files and the specfic programs required to update and maintain those files so that changes in programs require changes to the data. - lack of flexibility - poor security - lack of data sharing and availability 6.2- The Database Approach to Management database management system (DBMS): software that permiits an organization to centralize data, manage them efficiently, and provide access to the stored data by application programs - DBMS relieves the programmer or end user from the task of understanding where and how the data are actually stored by separating the LOGICAL and PHYSICAL views of the data. LOGICAL: presents data as they would be perceived by end users or business specialists PHYSICAL: shows how the data are actually organized and structured on physical storage media How a DBMS Solves the Problems of the Traditional File Environment - enables the organization to centrally manage their data Relational DBMSs relational DBMS: A type of logical database model that treats data as if they were stored in 2-D tables (aka relations or tuples). It can relate data stored in one table to data stored in another as long as the 2 tables share a common data element. fields = columns tuples: A row or record in a relational database key field: A field in a record that uniquely identifies instances of that record so that it can be retrieved, updated or sorted. primary key: Unique identifier for all the info in any row of a database table foreign key: Field in a database that enables users to find related info in another database table Operations of a Relational DBMS - in a relational database, 3 basic operations are used to develop useful sets of data 1. SELECT : creates a subset consisting of all records in the file that meet stated criteria. 2. JOIN: combines relational tables to provide user with more info than is available in individual tables 3. PROJECT: creates a subset consisting of columns in a table, permitting the user to create new tables that contain only the information required. Object-Oriented DMSs object-oriented DBMS: store the data and procedures that act on those data as objects hat can be automatically retrieved and shared. - they are becoming more popular because they can be used to manage the various multimedia components or Java applets used in Web applications, which typically integrate pieces of info from a variety of sources. - although OODMSs can store more complex types of info than relational DBMSs, they are relatively slower for processing large numbers of transactions object-relational DBMSs : Hybrid of OODMSs and DMSs , with the capabilities of both. Capabilities of Database Managemen Systems data definition: capability to specify the structure of the content of the database. it is used to create database tables and to define the characteristics of the fields in each table. data dictionary: an automated or manual file that stores definitions of data elements and their characteristics. Querying & Reporting data manipulation: A language associate with a database management system that end users and programmers use to manipulate data in the database. - microsoft access has a rudimentary data dictionary that displays information about the size, format, and other characteristics about each field in a database. Structured Query Language:The standard data manipulation language for relational database management systems. Designing Databases - the database requires both conceptual design and physical design - the conceptual/logical design of a a database is an abstract model of the database from a business perspective while the physical design shows how the database is actually arranged on direct-access storage devices. Normalization and Entity-Relationship Diagrams normalization: The process of creating small, stable, yet flexible and adaptive data structures from complex groups. - An unnormalized relation contains repeating groups. repeating data groups: Unnormalized data wherein there can be multiple records associated with high-impact loads or thousands of repetitions with low-impact loads. referential integrity: Rules to ensure that relationships between linked database tables remains consistent. entity-relationship diagrams: A methodology for documenting databases illustrating the relationship between various entities in the database. Dsitributing Databases distributed database: one that is stored in more than one physical location. - PARTITIONED -REPLICATE - reduce the vulnerability of a single massive site. 6.3 - Using Databases to Improve Business Performance ad Decision Making Data Warehouses data warehouse: a database that stores current and historical data of potential interest to decision maker throughout the company. - the data warehouse makes the data available for anyone to access as needed, but it can’t be altered. - the data warehouse extracts current and historical data from multiple operational systems inside
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