Topic 02 : Database & DBMS


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Topic 02 : Database & DBMS

  1. 1. TOPIC 2 : DATABASES & DBMS Er. Pradip Kharbuja
  2. 2. Metadata Metadata is data about data. It is the way in which the database keeps information about its own structure. Metadata is stored in the data dictionary.
  3. 3. Metadata Name Type Length Description Student Name Character 50 Student’s name Student ID Number 8 Unique identification number for a student Date of Birth Date 8 Student’s date of birth in the format ’01.01.80’
  4. 4. Metadata in MS Access
  5. 5. Metadata in Oracle SQL SQL> DESC emp Name Null? Type ------------------------------------------- EMPNO NOT NULL NUMBER(4) ENAME VARCHAR2(10) JOB VARCHAR2(9) MGR NUMBER(4) HIREDATE DATE SAL NUMBER(7,2) COMM NUMBER(7,2) DEPTNO NUMBER(2) SQL>
  6. 6. Metadata in SQL Server
  7. 7. Metadata ColumnName Type Length NULL Key Datatypes 1.VARCHAR 2.TEXT 3.INTEGER 4.DECIMAL 5.DATE
  8. 8. Activity Define metadata for data about the following: Students in a college database College Examination Books in a library system Holidays booked by a person at a workplace Shopping Mart Try to think about what data needs to be kept -will it be a character, date or number?
  9. 9. Two-File Processing System Customer File User Customer Processing System Rental Processing System Customer File Rental File Rental File User
  10. 10. Two-File Processing System The example used is of a car rental system. One system processes CUSTOMER data, and the other processes RENTAL data. Each of the files and the applications that use them are totally separate. Although this is an improvement over older manual systems, there are a number of problems.
  11. 11. Problems in Two-File Processing System 1.Data are separated and isolated. 2.Data are often duplicated. 3.Problem of Data integrity 4.Application programs are dependent on file formats. 5.It is difficult to represent data in a user’s perspective.
  12. 12. Basic Structure of a Database Customer Processing Application Rental Processing Application Other Application DBMS User User User Database
  13. 13. Database System in Detail DATA Customer Processing Application Rental Processing Application Other Application Database DBMS User User User METADATA Database Management System Application Requests Data Data Data Application Requests Application Requests DBMS serves as intermediary between user and the database by translating user requests into the complex code required to fulfill those requests. Application programsmight be written in a programming Language, such as Visual Basic or C++, or it might be created through a DBMS utility e.g. Access’s forms wizard.
  14. 14. DBMS DBMS serves as intermediary between user and the database by translating user requests into the complex code required to fulfill those requests. DBMS stands for data base management system. This is a software system which facilitates the formation, maintenance as well as use of an electronic database. It permits organizations to suitably develop databases for a range of applications by database administrators and certain specialists.
  15. 15. Features of the Database Approach 1.Integrated data 2.Reduced data duplication 3.Program/data independence 4.Easier representation of users’ perspectives
  16. 16. Common Applications 1.Forms 2.Reports 3.Web-applications 4.Desktop Applications
  17. 17. DBMS –Architecture •The DBMS is the software that handles all the interactions between applications and the database. •Paul Benyon-Davis provides a useful way of looking at the structure of the DBMS itself i.e. DBMS Architecture. •3 layers 1.Kernel 2.Interface 3.Toolkit
  18. 18. Kernel, Interface and Toolkit DBMS Toolkit Interface DBMS Kernel Database
  19. 19. Kernel, Interface and Toolkit 1.Kernel Central engine, which operates most of the core data management functions 2.Toolkit The tools and applications that interact with the end-users. These might be provided as part of the DBMS product or as separate piece of software. 3.Interface It handles the interaction between the toolkit and the kernel
  20. 20. DBMS Functions 1.CRUD functions 2.Data dictionary 3.Transaction management 4.Concurrency control 5.Recovery 6.Authorization 7.Data integrity 8.Administration utilities
  21. 21. Advantages of DBMS Control of data redundancy Improved data integrity or Data consistency Sharing of data Improved security Enforcement of standards Improved data accessibility and responsiveness Improved maintenance Increased concurrency Improved backup and recovery services
  22. 22. Disadvantages of DBMS Complexity Size Cost of DBMSs Additional hardware costs Cost of conversion Performance Requires skilled manpower
  23. 23. Data Models Hierarchical Network Relational Object-oriented Deductive Post-relational
  24. 24. References  
  25. 25. ANY QUESTIONS?