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ITD2011- Introduction to MIS. جـامعـــة الـجــزيــرة. UNIVERSITY OF JAZEERA. Dr. Mohamed Sammouda. Organizing Data and Information. Chapter 2. Principles and Learning Objectives.
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ITD2011- Introduction to MIS جـامعـــة الـجــزيــرة UNIVERSITY OF JAZEERA Dr. Mohamed Sammouda
Organizing Data and Information Chapter 2
Principles and Learning Objectives • Define general data management concepts and terms, highlighting the advantages and disadvantages of the database approach to data management. • Name three database models and outline their basic features, advantages, and disadvantages. • Identify the common functions performed by all database management systems and identify three popular end-user database management systems • Identify and briefly discuss recent database applications.
The Hierarchy of Data • Data is generally organized in a hierarchy that begins with the smallest piece of data used by the computers (a bit) and progresses through the hierarchy of Database. • Character: the basic building block of information, consisting of uppercase or lowercase letters, numeric digits, or special symbols. • Field: typically a name, number, or combination of characters that describes an aspect of a business object or activity. • Record: a collection of related data fields. • File: a collection of related records. • Entity: generalized class of people, places, or things for which data is collected, stored, and maintained. • Attribute: A characteristic of an entity. • Data item: the specific value of an attribute.
Keys and Attributes Key: a field or set of fields in a record that is used to identify the record. Primary key: a field or set of fields that uniquely identifies the records.
The Traditional Approach To Data Management • One of the most basic ways to manage data is via files. File is a collection of related records, all records associated with a particular application. • Traditional approach to data management: an approach whereby separate data files are created and stored for each application program. • With traditional approach, one or more data files is created and used for every application. • Data redundancy: is the duplication of data in separate files. • Data integrity: the degree to which the data in any file is accurate, therefore, conflicts with data redundancy.
The Database Approach to Data Management • Database approach to data management is a more efficient and effective means of organizing data, with a pool of related data shared by multiple application programs. • To use the database approach to data management, additional software a database management system (DBMS) is required. • Database management system (DBMS) is a group of programs that manipulate the database and provide an interface between the database and the user of the database and other application programs.
Data Modeling and Database Models • A database should be designed to store all data relevant to the business and provide quick access and easy modification. Also it must reflect the business process of the organization. • When building a database, careful consideration must be given to these questions: • Content: What data should be collected and at what cost? • Access: What data should be provided to which users and when? • Logical structure: How should data be arranged so that it makes sense to a given user? • Physical organization: Where should data be physically located?
Data Modeling and Database Models • Building a database requires two different type of designs: a logical design and physical design. • Logical design involves identifying relationships among the different data items and grouping them in an orderly fashion. • Physical design starts from logical design and fine-tunes it for performance and cost consideration (improve response time, reduced storage space, lower operating cost)
Data Modeling and Database Models • One of the tools database designers use to show the logical relationships among data is the data model. • Data model is a diagram of data entities and their relationships. • Data modeling usually involves understanding a specific business problem and analyzing the data and information needed to deliver a solution. • Enterprise data modeling: data modeling done at the level of the entire enterprise. • Entity-relationship (ER) diagrams: a data model that uses basic graphical symbols to show the organization of and relationships between data.
Entity-Relationship Diagram for a Customer Ordering Database
Database Models • Hierarchical (tree): a data model in which data is organized in a top-down, or inverted three structure. The hierarchical model is best suited to situations in which the logical relationships between data can be properly represented with the one-to-many approach. (child has only one parent) • Network: in this model there is an owner-member relationship in which a member may have many owners. So this model is capable of supporting many-to-many relationships.
Database Models • Relational: a database model that describes data in which all data elements are placed in two-dimensional tables, called relations, that are the logical equivalent of files. • The tables in relational databases organize data in rows and columns, simplifying data access and manipulation. • In this model, each row of a table represents a data entity, with the columns of the table representing attributes. Each attributes can take on only one value. The allowable values for these attributes are called the domain.
Relational Models Once data has been placed into a relational database, users can make inquires and analyze data. Basic data manipulation include selecting, projecting, and joining. • Selecting involves choosing rows according to certain criteria. (find the department number for the project 226) • Projecting involves choosing columns in a table. (create new table having only department number and SSN) • Joining involves combining two or more tables. (we can combine the project table and department table to get new table with the project numbers, project description, department name, and social security number for the manager in charge of the project) As long as the tables share at least one common data attributes, therefore these tables can be linked to provide a useful information and reports.
Providing a User View • DBMS is responsible for access to a database. Installing and using a database involves defining the logical and physical structure of the data and relationships among the data in the database. • Schema - a description of the entire database • Subschema - a file that contains a description of a subset of the database and identifies which users can modify the data items in that subset
Creating and Modifying the Database • Data definition language (DDL) - a collection of instructions and commands used to define and describe data and data relationships in a specific database • Data dictionary – detailed description of data in a database • Data manipulation language (DML): commands that are used to manipulate the data in a database.
Typical Uses of a Data Dictionary • Provide a standard definition of terms and data elements • Assist programmers in designing and writing programs • Simplify database modification • Reduce data redundancy • Increase data reliability • Speed program development • Ease modification of data and information Administering Databases Database administrator (DBA): a highly skilled and trained systems professional who directs or performs all activities related to maintaining a successful database environment. Data Administrator: a non-technical but important person who ensures that data is managed as an important organizational resource.
Database Features • Tables • Records • Fields • Record sorting • Queries • Forms • Reports
Popular Database Management Systems • Paradox database • FileMaker Pro • Microsoft Access • Lotus 1-2-3 Spreadsheet
Selecting a Database Management System • Database size: depends on the number of records or files in the database. • Number of concurrent users: the number of simultaneous users that can access the contents of the database. • Performance: how fast the database can update records can be the most important criteria for some organization. • Integration: the ability to integrate with other application and database. • Features: the security procedures, privacy protection and a variety of tools. • Vendor: the size, reputation, and financial stability of the vendor should also be considered in making and database purchase. • Cost: database packages for personal computers can cost a few hundred dollars, while large database systems for mainframe computers can cost hundreds of thousand of dollars.
Data Warehouses, Data Marts, and Data Mining • Data Warehouse - a database that collects business information from many sources in the enterprise, covering all aspects of the company’s processes, products, and customers. – data warehouse provides business users with a multidimensional view of the data they need to analyze business conditions. • Data Mart – a subset of a data warehouse. – rather than store all enterprise in one monolithic database, data marts contain a subset of the data for the single aspect of a company’s business. • Data Mining - an information analysis tool that involves the automated discovery of patterns and relationships in a data warehouse.
Object-Relational Database Management System • A DBMS capable of manipulating the following types of data as objects: • audio • images • unstructured • text • spatial data
Summary • Data - one of the most valuable resources a firm possesses. • Entity - a generalized class of objects for which data is collected, stored, and maintained. • Attribute - a characteristic of an entity. • DBMS - a group of programs used as an interface between a database and application programs. • Data mining - the automated discovery of patterns and relationships in a data warehouse.
