CHAPTER 10:MANAGING A DATABASE

Database,Data,and Information

• Database
• Collection of data organized in a manner that allows access,retrieval,and use of that data.
• Data
• Collection of unprocessed items
• Text
• Numbers
• Images
• Audio
• Video
• Information
• Processed data
• Documents
• Audio
• Images
• Video
• 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
• Data integrity identifies the quality of the 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:
• Accurate
• Verifiable
• Timely
• Organized
• Accessible
• Useful
• Cost-effective

The Hierarchy of Data

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

Maintaining Data

• File maintenance refers to the procedure that keep data current
• Adding records
• Modifying records
• Deleting records
• Users add new records to a file when they obtain new data.
• Users modify a record to correct inaccurate data or update old data.
• When a record no longer is needed,a user deletes it from a file.
• 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

• File processing system
• Each department has its own set of files
• Used for many years
• Have data redundancy
• Isolate data
• 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

• A data dictionary contains data about each file in the database and each field in those files.
• 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.
• Form
• is a window on the screen that provides areas foe entering or modifying data in a database.
• Report generator
• allows users to design a report on the screen,retrieve data into the report design,and then display or print the report.

How to Use the Simple Query Wizard

Step 1: Select the fields from the Available Fields list you want to be displayed in the resulting query.

Step 2: Assign a name to the query,so that you can open it later.

Step 3: View the query results on the screen.

• A DBMS provides means to ensure that only authorized users access data at permitted times.
• Access privileges
• Principle of least privilege
• A DBMS provides a variety of techniques to restore the database to usable form in case it is damaged or destroyed
• Backup
• Log
• Recovery utility
• Continuous backup

Relational,Object-Oriented,and Multidimensional Databases

• A data model consists of rules and standard that define how the database organizes data.
• A 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.
• An object-oriented database (OODB) stores data in object.
• Examples of applications appropriate for an object-oriented database include:
• Multimedia database
• Groupware database
• Computer-aided design database
• Hypertext database
• A 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
• A data warehouse is a huge database that stores and manages the data required to analyze historical and current transactions.

Web Databases

• Databases on the Web 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

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
• Employees should learn how to use the data in the database effectively
• Interact with database
• Identify new data for the database
• Maintain the database