Chapter 10 : Managing A Database

What is Database,Data,and Information?

1. Database is collection of data organized in a manner that allows access,retrieval,and use of that data.
2. Data is collection of unprocessed items such as:
• Text
• Numbers
• Images
• Audio
• Video
• Information
• Processed data
• Documents
• Audio
• Images
• Video
3. Database software,often called a database management system (DBMS),allows users to
• Create a computerized database
• Add,modify,and delete data
• Sort and retrieve data
• Create forms and reports from the data
4. Garbage in,garbage out (GIGO) points out the accuracy of a computer's output depends on the accuracy of the input.
5. Valuable information should have the following characteristics:

• Accurate
• Verifiable
• Timely
• Organized
• Accessible
• Useful
• Cost-effective

The Hierarchy of Data

1. Character character is only byte, numbers,letters,space,punctuation marks,or other symbols.
2. Field is a combination of one or more related characters
• Field name
• Field size
• Data type
3. Common data types include:
• Text
• Numeric
• AutoNumber
• Currency
• Date
• Memo
• Yes/No
• Hyperlink
• Object
• Attachment
• Record
4. A record is a group of related fields. A primary key uniquely identifies each record.
5. A data file is a collection of related records.

What to maintaining Data?

1. File maintenance refers to the procedure that keep data current:
• Adding records-Users add new records to a file when they obtain new data.
• Modifying records-Users modify a record to correct inaccurate data or update old data
• Deleting records-When a record no longer is needed,a user deletes it from a file.
2. Validation compares data with a set of rules or values to find out if the data is correct:
• Alphabetic/Numeric check
• Range check
• Consistency check
• Completeness check
• Check digit
• Other checks

File Processing Versus Databases: Let's see which one is more convenient.

1. File processing system: 
• Each department has its own set of files
• Used for many years
• Have data redundancy
• Isolate data
2. Database approach
• Programs and users share data
• Reduce data redundancy 
• Improve data integrity
• Share data
• Allows easier
• Reduces development time
• Can be more vulnerable

Database Management Systems

1. A data dictionary contains data about each file in the database and each field in those files.
2. A DBMS provides several tools that allow users and programs to retrieve and maintain data in the database:
• Query language consists of simple,English-like statements that allow users to specify the data to display,print,or store. Query by example (QBE) provides a GUI to assist users with retrieving data.
3. Form is a window on the screen that provides areas foe entering or modifying data in a database.
4. Report generator allows users to design a report on the screen,retrieve data into the report design,and then display or print the report.
5. A DBMS provides means to ensure that only authorized users access data at permitted times.
6. A DBMS provides a variety of techniques to restore the database to usable form in case it is damaged or destroyed. There are:
• Backup
• Log
• Recovery utility
• Continuous backup

Relational,Object-Oriented,and Multidimensional Databases

1. A data model consists of rules and standard that define how the database organizes data.
2. A relational database stores data in tables that consists of rows (each row has a primary key) and columns (each columns has a unique name).
3. A relationship is a link within the data.
4. Structured Query Language (SQL) is a query language that allows users to manage,update,and retrieve data.
5. An object-oriented database (OODB) stores data in object.
6. Examples of applications appropriate for an object-oriented database include:
• Multimedia database
• Groupware database
• Computer-aided design database
• Hypertext database
7. A multidimensional database can store data in more than two dimensional of data and sometimes known as a hyper-cube. It can consolidate data much faster than a relational database
8. A data warehouse is a huge database that stores and manages the data required to analyze historical and current transactions.
9. Web Databases allow you to:
• Shop for products or services
• Buy or sell stocks
• Search for a job
• Make airline reservations
• Register for college classes
• Check semester grades
10. Database Administration. It is important to have a carefully designed database. Database analysts and administrators are responsible for managing and coordinating all database activities.
• Database Analyst (DA)-Decides on proper field placement,defines data relationship,and identifies user's access privileges.
• Database Administrator (DBA)-Creates and maintains the data dictionary,manages security,monitors performance,and checks backup and recovery procedures.
11. Employees should learn how to use the data in the database effectively:
• Interact with database
• Identify new data for the database
• Maintain the database