Chapter 10 - Managing a Database

A Database is a collection of information that is organized so that it can easily be accessed, managed, and updated. In one view, databases can be classified according to types of content: bibliographic, full-text, numeric, and images.

Database is a collection of data organized in a manner that allows accessing retrieval and use of that data.
Data  is a collection of unprocessed items such as text, number, images, video, and audio.
Information is where it processed data such as documents. images, video, and audio.
Database software,often called a database management system (DBMS), allows users to create a computerized database, create forms and reports from the data, sort and retrieve data and modify and delete data.
Garbage in, garbage out (GIGO) points out the accuracy of a computer's output depends on the accuracy of the input .

Valuable information should have the following characteristics:

1.Accurate
2.Verifiable
3.Timely
4.Organized
5.Accessible
6.Useful
7.Cost-effective

 

The Hierarchy Of Data:

1.Character
2.Field
3.Records
4.Files

File maintenance refers to the procedure of adding, modifying and deleting records.(Adding , deleting, modify records )
Validation compares data with a set of rules or values to find out if the data is correct.
Database validation is required when databases get corrupted to check for corruption.

Types of validity checks:
1. Alphabetic/Numeric check
2. Range check
3. Consistency check
4. Completeness check
5. Digit check

File processing versus Database approach.
File processing system:
1.Each department has its own set of files.
2. Have data redundancy.
3. Isolate data.

Database approach:
1. Programs and users share data.
2. Reduce data redundancy.
3. Improve data integrity.
4. Share data.
5. Allow easier access.
6. Reduce development time.
7. More vulnerable.

Database Management Systems
1. Data dictionary- contains data about each file in the database and each field in those lines.
2. Query language- consist of simple, english like statements that allow users to specify the data to display, print or store.
3. Query by example (QBE)- provide a graphical user interface to assist users with retrieving data.
4. Form- window on the screen that provide areas for entering or modifying data in a database.
5. Report generator- allows users to design a report on the screen, retrieve data into the report design and then display or print the report.

Relational,Object-Oriented,and Multidimensional Databases

Data model consists of rules and standard that define how the database organizes data. 

Relational database stores data in tables that consists of rows and columns. 
-Each row has a primary key. 
-Each columns has a unique name. 
-A relationship is a link within the data. 

Structured Query Language (SQL) is a query language that allows users to manage,update,and retrieve data. 
Object-oriented database (OODB) stores data in object. 
Examples of applications appropriate for an object-oriented database include: 
1.Multimedia database 
2.Groupware database 
3.Computer-aided design database 
4.Hypertext database 

Multidimensional database can store data in more than two dimensional of data. 
sometimes known as a hypercube 
Can consolidate data much faster than a relational database 
Data warehouse is a huge database that stores and manages the data required to analyze historical and current transactions.