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Database Management System

Database Management System

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Database Management System

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  1. Database Management System

  2. Data and Information • How are data and information related? • Data is raw facts • Information is data that is organizedand meaningful • Computers process data into information Step 2. The computer extracts the member data from disk. receipt processing Step 1. The member data, including a photograph, is entered and stored on the hard disk. data stored on disk Step 3. The receipt is created and printed.

  3. Collection of data organized so you can access, retrieve, and use it Database software allows you to Database software also called database management system (DBMS) Createdatabase Createforms and reports Add, change, and delete data Sort and retrieve data Data and Information • What is a database?

  4. What is DBMS? • A set of programs is provided to facilitate the users in organizing, creating, deleting, updating, and manipulating their data in a database. All these manipulation form aDatabase Management System (DBMS).

  5. Data and Information Garbage in • What is data integrity? • Degree to which data is correct • Garbage in, garbage out (GIGO)—computer phrase that means you cannot create correct information from incorrect data Garbage out Data integrity is lost

  6. Accurate Verifiable Timely Organized Accessible Useful Cost-effective Data and Information • What are the qualities of valuable information?

  7. The Hierarchy of Data • What is a hierarchy? • Database contains files, file contains records, record contains fields, field contains characters

  8. The Hierarchy of Data • What is a field? • Combination of one or more characters • Smallest unit of data user accesses • Field sizedefines the maximum number of characters a field can contain • Field name uniquely identifies each field • Data typespecifies kind of data field contains

  9. Text (also called alphanumeric)—letters, numbers, or special characters Numeric numbers only AutoNumber unique number automatically assigned to each new record Currency dollar and cent amounts or numbers containing decimal values Date month, day, year, and sometimes time Memo lengthy text entries Object (also called BLOB for binary large object)—photograph, audio, video, or document created in other application such as word processing or spreadsheet Yes/No (also called Boolean)—only the values Yes or No (or True or False) Hyperlink Web address that links to document or Web page What are common data types?

  10. The Hierarchy of Data • What is a record? Group of related fields Key field, or primary key, uniquely identifies each record

  11. Member ID • First Name • Last Name • Address • City • State • 2295 • Donna • Vandenberg • 1029 Wolf Avenue • Montgomery • AL • 2928 • Shannon • Murray • 33099 Clark Street • Montgomery • AL • 3376 • Adrian • Valesquez • 15 Duluth Street • Prattville • AL • 3928 • Jonah • Weinberg • P.O. Box 45 • Clanton • AL • 4872 • Marcus • Green • 22 Fifth Avenue • Auburn • AL records key field fields The Hierarchy of Data • What is a data file? • Collection of related records stored on disk

  12. Adding records Changing records Deleting records Maintaining Data • What is file maintenance? • Procedures that keep data current

  13. Maintaining Data • Why do you add records? • Add new record when you obtain new data

  14. Maintaining Data • Why do you change records? • Correct inaccurate data • Update old data

  15. Maintaining Data • Why do you delete records? • When record no longer is needed • Some programs remove record immediately, others flag record

  16. SAMPLE VALID AND INVALID DATA • Validity Check • Field Being Checked • Valid Data • Invalid Data • Alphabetic Check • First Name • Adrian • Ad33n • NumericCheck • Postal Code • 36109 • 3rto9 • Range Check • Monthly Fee • $39.50 • $95.25 • Consistency • Check • Date JoinedTraining Date • 10/20/200510/27/2005 • 10/20/200510/13/2005 • Completeness • Check • Last Name • Valesquez Maintaining Data • What is validation? • Process of comparing data with a set of rules to find out if data is correct • Reduce data entry errors and enhance data integrity before program writes data on disk

  17. Check Digitnumber(s) or character(s) appended to or inserted into a primary key value to confirm accuracy of primary key value Alphabetic/Numeric Check ensures correct type of data entered Completeness Checkverifies that a required field contains data Consistency Checktests for logical relationship between two or more fields Range Check determines whether number is within specified range Maintaining Data • What are the types of validity checks?

  18. Each department or area within organization has own set of files Records in one file may not relate to records in any other file May have weaknesses Data redundancy—same fields stored in multiple files Isolated data—data stored in separate files so it is difficult to access File Processing Versus Databases • What is a file processing system?

  19. File Processing Versus Databases • What is the database approach? • Many programs and users can share data in database • Secures data so only authorized users can access certain data

  20. Reduced data redundancy Improved data integrity Shared data Easier access Reduced development time File Processing Versus Databases • What are the strengths of the database approach?

  21. File Processing Versus Databases • How do a database application and a file processing application differ in the way they store data?

  22. Database • Manufacturer • Computer Type • Access • Microsoft Corporation • Personal computer, server, PDA • DB2 • IBM Corporation • Personal computer, midrange server, mainframe • Informix • IBM Corporation • Personal computer, midrange server, mainframe • Ingres • Computer Associates International, Inc. • Personal computer, midrange server, mainframe • Oracle • Oracle Corporation • Personal computer, midrange server, mainframe, PDA • SQL Server • Microsoft Corporation • Server • Sybase • Sybase Inc. • Personal computer, midrange server, PDA Database Management Systems • What are popular database management systems (DBMSs)?

  23. Database Management Systems • What is a data dictionary? • Contains data about each file in database and each field within those files

  24. Database Management Systems Step 1. Select the fields you want to display in the resulting query. • What is a query? • Request for specific data from a database • Query language consists of simple, English-like statements that allow users to specify data to display, print, or store Step 2. Assign a name to the query, so you can open it later. Step 3. View query on the screen.

  25. Database Management Systems • 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 Query by example screen criteria Query results

  26. Database Management Systems • 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 • Form that sends data across network or Internet is called e-form, short for electronic form

  27. Access privileges define activities that specific user or group of users can perform DBMS provides means to ensure only authorized users can access data Read-only privileges user can view data, but cannot change it Full-update privileges user can view and change data Database Management Systems • What is data security?

  28. Database Management Systems before image • What are backup and log? • Backup is a copy of the entire database • Logis a listing of activities that change database contents • DBMS places three items in log: before image, actual change, and after image change after image

  29. Data model • A database model defines the manner in which the various files of a database are linked together. The four commonly used database models are : • Hierarchical Databases • Network Databases • Relational Databases • Object-oriented databases

  30. Relational, Object-Oriented, and Multidimensional Databases DATA MODELS FOR POPULAR DBMSs • 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

  31. Relational, Object-Oriented, and Multidimensional Databases • What is a relational database? • Stores data in tables that consist ofrows and columns • Each row has primary key • Each column has unique name • Stores data relationships • Uses specialized terminology DATA TERMINOLOGY

  32. Relational Database • A relational database, the data elements are organized in the form of multiple tables with rows and columns. • Each table of the data base is stored as a separate file, and each row a data record (also known as a tuple). • The data in one table (or file) is related to data in another table with a common field.

  33. Organization Personal Dept Finance Dept Technical Dept Manger Staff Manger Staff Manger Engineers Techni cians Staff Hierarchical Databases A Parent element A child element

  34. College English Bangla Maths Computer science khaled Lailun Jasmine Karim Shown Rajas An example of a network database Network Databases

  35. Object-oriented database • The hierarchical, network, and relational database models were developed for the conventional business data processing applications, such as inventory control, payroll, employee information system, and so on. • Attempts to make use of these database models in a wide variety of other types of applications, exposed several serious shortcomings of these database models.

  36. Objectis item that contains data, as well as actions that read or process data Stores data in objects • Can store more types of data • Can access data faster Advantages Often uses object query language (OQL) Relational, Object-Oriented, and Multidimensional Databases • What is an object-oriented database (OODB)?

  37. Uses logs and/or backups to restore database when it is damaged or destroyed • Rollforward—DBMS uses log to re-enter changes made to data-base since last save or backup • Also called forward recovery • Rollback— DBMS uses log to undo any changes made to database during a certain period of time • Also calledbackward recovery Database Management Systems • What is arecovery utility?

  38. Relational, Object-Oriented, and Multidimensional Databases • What is a relationship? • Connection within data

  39. Relational, Object-Oriented, and Multidimensional Databases • What is Structured Query Language (SQL)? • Allows you to manage, update, and retrieve data • Has special keywords and rules included in SQL statements SQL statement SQL statement results

  40. Multimedia databases Hypertext databases Hypermedia databases Web databases Store images, audio clips, and/or video clips Contain text links to other documents Contain text, graphics, video, and sound Link to e-form on Web page Groupware databases Store documents such as schedules, calendars, manuals, memos, and reports Computer-aided design (CAD) databases Store data about engineering, architectural, and scientific designs Relational, Object-Oriented, and Multidimensional Databases • What are examples of applications appropriate for an object-oriented database?

  41. Stores data in dimensions Multiple dimensions, also called hypercube, allow users to analyze any view of data Can consolidate data much faster than relational database Relational, Object-Oriented, and Multidimensional Databases • What is a multidimensional database?

  42. Huge database system that stores and manages data required to analyze historical and current transactions Quick and efficient way to access large amounts of data Often uses a process called data mining to find patterns and relationships among data Data mart is smaller version of data warehouse Uses multidimensional databases Relational, Object-Oriented, and Multidimensional Databases • What is a data warehouse?

  43. Web Databases • 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

  44. Web Databases • How might a search engine interact with a Web database? Step 1. Browser sends search text to Web server. Step 2. Web server sends search text through a CGI script to database. Database retrieves list of hits that contains search text and sends it through CGI script back to Web server. Step 3. Web server sends list of hits to browser.

  45. 2. Design the tables 3.Design the records and fields for each table Database Administration • What are guidelines for developing a database? 1. Determine the purpose of the database • Design tables on paper first • Each table should contain data about one subject • 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 entered data 4. Determine the relationships among the tables

  46. Database administrator (DBA) Database analyst (DA) • Focuses on meaning and usage of data • Decides proper placement of fields, defines relationships, and identifies users’ access privileges • Creates and maintains data dictionary, manages database security, monitors database performance, and checks backup and recovery procedures Database Administration • What is the role of the database analyst and administrator?

  47. Main Components of a DBMS • The four major components of a DBMS are : • Data Definition Languages (DDL) • Data Manipulation Languages (DML) • Query Language, and • Report Generator.

  48. Data Definition Languages (DDL) • A Data Definition Languages (DDL)is used to define the structure of a database. The database structure definition is commonly known as database schema.

  49. Data Manipulation Languages (DML) • The Data Manipulation Languages (DML)includes all the commands that enable the users to enter and manipulate the data.

  50. Query Language • TheQuery Languageenables users to define their requirements for extracting the desired information from the database in the form of queries.