WEEK 07
REFLECTION IN THIS WEEK
This week what I have learned is what you can see in this page. I have learned the Database as well as the Database Management System. Database a collection of interrelated data stored together with controlled redundancy to serve one or more applications in an optimal way. The data are stored in such a way that they are independent of the programs used by the people for accessing the data. Database Management System a software system for manipulating databases.
Apply relational database design approach and implement it using Microsoft Access or other DBMS
Introduction
•Database: A collection of interrelated data stored together with controlled redundancy to serve one or more applications in an optimal way. The data are stored in such a way that they are independent of the programs used by the people for accessing the data.
•Database Management System: a software system for manipulating databases.
Database Components
•Data item: It is defined as a distinct piece of information and is explained in the previous section.
•Relationships: It represents a correspondence between various data elements.
•Constraints: These are the predicates that define correct database states.
•Schema: It describes the organization of data and relationships within the database. The schema consists of definitions of the various types of record in the database, the data-items they contain and the sets into which they are grouped. The storage structure of the database is described by the storage schema. The conceptual schema defines the stored data structure. The external schema defines a view of the database for particular users.
Database Management Systems
The DBMS performs the following five primary functions:
•Define, create and organise a database: The DBMS establishes the logical relationships among different data elements in a database and also defines schemas and subschemas using the DDL.
•Input data: It performs the function of entering the data into the database through an input device (like data screen, or voice activated system) with the help of the user.
•Process data: It performs the function of manipulation and processing of the data stored in the database using the DML.
•Maintain data integrity and security: It allows limited access of the database to authorised users to maintain data integrity and security.
•Query database: It provides information to the decision makers that they need to make important decisions. This information is provided by querying the database using SQL
Examples of DBMS
•Microsoft Access
•Oracle
•IBM DB2
•SQL Server
•MySQL
Database System
The DBMS software together with the Database is called a database system. It can be defined as an organization of components that define and regulate the collection, storage, management and use of data in a database. It is a system whose overall purpose is to record and maintain information.
Advantages of Database Systems
1.Controlled redundancy
2.Data consistency
3.Sharing of data
4.Improved data integrity
5.Improved security
6.Data access is efficient
Types of Database Models
•Hierarchical database
•Network database
•Relational database
•Object-relational database
Hierarchical database
•The hierarchical data model organizes data in a tree structure.
•There is a hierarchy of parent and child data segments.
•This structure implies that a record can have repeating information, generally in the child data segments.
•Hierarchical DBMSs were popular from the late 1960s, with the introduction of IBM’s Information Management System (IMS) DBMS, through the 1970s
Network database
•Resembles hierarchical model.
•Difference child can have multiple parents.
•Some data were more naturally modeled with more than one parent per child.
•The network model permitted the modeling of many-to-many relationships in data.
Relational Database
•In relational databases, fields can be used in a number of ways (and can be of variable length), provided that they are linked in tables.
•It is developed based on a database model that provides for logical connections among files (known as tables) by including identifying data from one table in another table.
•Tables comprise the fundamental building blocks of any database.
•Relation, basically a table with rows and columns.
Database terminology
Structured Query Language (SQL)
•Pronounced either see-kwell or as separate letters.
•Widely used non-procedural language.
•“Invented” at IBM’s Almaden Research Centre (San Jose, CA) in the 1970s.
•SQL is a standardized query language for requesting information from a database.
Object-relational database
•Object-relational database management system (ORDBMS)
•A DBMS capable of manipulating audio, video, and graphical data.
•Hypertext
•Users can search and manipulate alphanumeric data in an unstructured way
•Hypermedia
•Allows businesses to search and manipulate multimedia forms of data
•Spatial data technology
•Use of an object-relational database to store and access data according to the location it describes and to permit spatial queries and analysis
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