Databases, Data and Information

  Database Management

  Add, change, and delete

  Add, change, and delete

  Create database

  Create database

  Sort and retrieve

  Sort and retrieve

  Create forms and reports

  Create forms and reports

  What is a database ?

  

Database software

  allows you to

  

Database software

allows you to

  Collection of data organized so you can access, retrieve, and use it

  Collection of data organized so you can access, retrieve, and use it

  Database software also called database

  management system (DBMS) Database software also called database management system (DBMS) How are data and information related?

Data is raw facts

  Information is data that is organized and meaningful

• Computers process data into information

  What is data integrity?

• Defines the quality of the

  Garbage in

  data

   Garbage in, garbage out (GIGO) — computer phrase that means you cannot create correct information

  Garbage out from incorrect data

  Data integrity

  Useful Useful Accessible Accessible Organized Organized

  What are the qualities of valuable information?

  Timely Timely Verifiable Verifiable Accurate Accurate What is a hierarchy?

• Database contains files, file contains records, record contains fields, field contains characters

What is a field ?

• Combination of one or more characters Smallest unit of data user accesses
•  Field name uniquely identifies each field

   defines the maximum number of  Field size characters a field can contain specifies kind of data field

   Data type contains

  Yes/No Yes/No only the values Yes or No

Hyperlink

  

Hyperlink

Web address that links to

  Object Object photograph, audio, video, or document created in other application such as What are common data types?

  Currency Currency dollar and cent amounts or numbers containing decimal values Date Date month, day, year, and sometimes time Memo Memo lengthy text entries Text Text (also called alphanumeric )— letters, numbers, or special characters

Numeric Numeric

numbers

only

  AutoNumber AutoNumber unique number automatically assigned to each new record What is a record ?

Group of related fields

  Key field , or primary key ,

  uniquely identifies each record What is a data file ?

• Collection of related records stored on disk

  key records fields

  22 Fifth Avenue P.O. Box 45

  15 Duluth Street 33099 Clark Street 1029 Wolf Avenue Address Auburn Clanton Prattville Montgomery Montgomery City AL Ruiz Adelbert ³⁹²⁸ AL Elena ⁴⁸⁷²

  AL Drake Louella ³⁸⁷⁶ AL Murray Shannon 2928 AL Brewer Milton 2295 State Last Name First Name Member ID Gupta Changing records Adding records Deleting records

  What is file maintenance ?

• Procedures that keep data current

Why do you add records?

• Add new record when you obtain new data

Why do you change records?

• Correct inaccurate data
• Update old data

Why do you delete records?

When record no longer is needed

  Some programs remove record immediately, others flag record

What is validation ?

• if data is correct Reduce data entry errors and enhance data integrity

  Process of comparing data with a set of rules to find out

• before program writes data on disk

Check Digit

Check Digit

Alphabetic/ Numeric Check

Completeness Check

Completeness Check

  ensures correct type

of data entered

Alphabetic/ Numeric Check ensures correct type

of data entered

Consistency Check

Consistency Check

  tests for logical relationship between two or more fields

  tests for logical relationship between two or more fields

  number(s) or character(s) appended to or inserted into a primary key value to confirm accuracy of primary key value

  verifies that a required field contains data

  verifies that a required field contains data

  

Range Check

determines whether number is within

specified range

  

Range Check

determines whether number is within

specified range

  What are the types of validity checks ?

  number(s) or character(s) appended to or inserted into a primary key value to confirm accuracy of primary key value

  Isolated data— data stored in separate files so it is difficult to

  Isolated data — data stored in separate files so it is difficult to

  What is a file processing system ? Data redundancy— same fields stored in

  Data redundancy — same fields stored in

  Each department or area within organization has own set of files

  Each department or area within organization has own set of files

  May have weaknesses

  May have weaknesses

  Records in one file may not relate to records in any other file

  Records in one file may not relate to records in any other file

What is the database approach ?

• Many programs and users can share data in database
• Secures data so only authorized users can access certain data

What are the strengths of the database approach?

  Reduced data redundancy Reduced data redundancy Improved data integrity Improved data integrity

Shared

data

  

Shared

data Easier access Easier access Reduced development Reduced development time How do a database application and a file processing application differ in the way they store data?

  

What are popular database management systems (DBMSs)?

  What is a data dictionary ?

• Contains data about each file in database and each field within those files

What is a query ?

• data from a database

  Request for specific

• consists of simple, English-like statements that allow users to specify data to display, print, or store

  Query language

What is a query by example (QBE) ?

• Program retrieves records that match criteria entered in form fields Has a graphical user interface that assists users with
• retrieving data

What is a form ?

• Window on screen that provides areas for entering or changing data in database
• Used to retrieve and maintain data in a database
• Well-designed forms should validate data as it is entered

What is a report generator ?

• into report design, then display or print reports Also called report

  

Allows user to design a report on screen, retrieve data

• writer

What are backup and log ?

• Backup is a copy of the entire database
• Log is a listing of activities that change database contents

   A recovery utility uses the logs and/or backups to restore a database when it becomes damaged or destroyed What is data security?

  Access privileges

  Access privileges

  DBMS provides

  DBMS provides

  define activities

  define activities

  means to ensure

  means to ensure

  that specific user

  that specific user

  only authorized

  only authorized

  or group of users

  or group of users

  users can access

  users can access

  can perform

  can perform

  data at permitted

  data at permitted

  times

  times

  user can view

  user can view

  user can view

  user can view

  data, but

  data, but

  and change

  and change

  cannot change

  cannot change

  data

  data

  it

  it What is a data model ?

• Rules and standards that define how database organizes data
• Defines how users view organization of data Three popular data models
• 

Relational

   Object-oriented

   Multidimensional What is a relational database ?

• Stores data in tables that consist of rows and columns

   Each row has primary key

   Each column has unique name

• Stores data relationships
• Uses specialized terminology

What is a relationship ?

• Connection within data

What is Structured Query Language (SQL) ?

• Allows you to manage, update, and retrieve data
• Has special keywords and rules included in SQL statements

What is an object-oriented database (OODB) ?

  Advantages

Often uses object query language (OQL)

Stores data in objects

  Object is item that contains data, as well as actions that read or process data

  Can store more types of data Can access data faster Programmers can reuse objects What is a multidimensional database ?

  Stores data in dimensions Allow users to analyze any view of data Can consolidate data much faster than relational database What is a data warehouse ?

  Data mart is smaller version of Data mart is smaller version of data warehouse data warehouse Uses multidimensional Uses multidimensional databases databases Huge database system that stores and manages data Huge database system that stores and manages data required to analyze historical and current transactions required to analyze historical and current transactions Quick and efficient Quick and efficient way to access large way to access large amounts of data amounts of data

What is a Web database?

• Database you access through the Web by filling in a form on a Web page
• Usually resides on a database server, a computer that stores and provides access to a database

  3. Design the records and fields for each table 2. Design the tables 1. Determine the purpose of the database 1. Determine the purpose of the database 4. Determine the relationships among 4. Determine the relationships among  Design tables on paper first  Each table should contain data about one subject

  What are guidelines for developing a database?  Be sure every record has a unique primary key  Use separate fields for logically distinct items  Do not create fields for information that can be derived from entries in other fields  Allow enough space for each field  Set default values for frequently

  What is the role of the database analyst and administrator?

Database administrator Database analyst (DA) Database administrator Database analyst (DA) (DBA) (DBA)

   Decides proper placement

   Creates and maintains data of fields, defines dictionary, manages relationships, and database security, identifies users’ access monitors database privileges performance, and checks backup and recovery procedures