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Presentation on Database management system

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It includes:
Introduction to Database Management System
DBMS vs File System
View of data
Data models
Database Languages: DML, DDL
Database users and administrators
Transaction Management
Database System Structure
Application architectures

Publicado en: Educación
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Presentation on Database management system

  1. 1. Getting started with DBMS Prepared By: Prerana Bhattarai
  2. 2. • Introduction to Database Management System • DBMS vs File System • View of data • Data models • Database Languages: DML, DDL • Database users and administrators • Transaction Management • Database System Structure • Application architectures The slides include:
  3. 3. • A DBMS is a collection of software programs that allows a user to define data types, structures, constraints, store data permanently, modify and delete the operations. • DBMS is basically a software used to add, modify, delete, select data from the database. • In simpler words, DBMS is a collection of interrelated data and software programs to access those data. Introduction to Database Management System
  4. 4. Bases DBMS Flat file system Definition Data redundancy Cost Use Views DBMS is a collection of interrelated data and software programs to access those data. There is no problem of data redundancy. DBMS software are very costly and also regular update makes it costly. Mostly, large organizations use DBMS who can afford it and have a large number of client and employees to be managed. Views are created and an employees can’t see all information available, hence there is security. Flat file system stores data in a plain text file. Here, the records are specified in a single line. There is main problem of data redundancy. Flat file are cost effective. Small organizations use it as it is cost effective and who have to deal with small number of clients and employees. Any information can be seen by anyone, hence there is no security. DBMS VS Flat file system
  5. 5. View 1 View 2 View N Logical level Physical level Views of data View level Conceptual level Internal level Stored database
  6. 6. • It is a process of easy user interface to users by hiding underlying complexities of data management from users. • It defines views; which user can view which part. • Database system provides users with abstract view of the data. • It only shows a part of database that a user needs. Data abstraction
  7. 7. • It is the lowest level of abstractions and describes how the data are stored on the storage disk and access mechanisms to retrieve the data. • DBMS developer is concerned with this level. • This level emphasis on minimizing the number of disks access so that data can be retrieved very fast. • It describes complex low-level data structures in detail. Physical Level
  8. 8. • This level describes what data are stored in the database and the relationships between the data. • It describes stored data in terms of the data model. • It describes the database in terms of small number of relatively simple structures. Logical Level
  9. 9. • Every user don’t need to access all information stored in the database. • This level is basically concerned with dividing the database according to the need of the database users. • It simplifies the interaction of the users with the system. View Level
  10. 10. • The basic design or the structure of the database is the data model. • It is a collection of conceptual tools for describing data, data relationships, data semantics, and consistency constraints. • The basic structure of the database that organizes data, defines how the data are stored and accessed, and the relationships between the data, is the data model. Data Model
  11. 11. • Hierarchical Model • Network Model • Entity-Relationship(E-R) Model • Relational Model • Object-Oriented Model • Object-Relational Model Types of database models
  12. 12. • Data is represented as a tree. • A record type can belong to only one owner type but a owner type can belong to many record type. Hierarchical Data Model
  13. 13. • It is modified version of Hierarchical Data Model where it allows more general connections among the nodes as well. • They are difficult to use but are more flexible than hierarchical databases. Network Data Model
  14. 14. • It is a lower level model that uses a collection of tables to represent both data and relationships among those data. • Each table has multiple columns, depending on the number of attributes, and each column has a unique name. Student sid sname Standard A-101 Ramesh 11 A-102 Kriti 10 A-103 Laxmi 12 Relational Model
  15. 15. • It is a high level model based on the need of the organization. • Its entities are distinguishable from other objects and relationship is an association among several entities. Student Borrows Books sid sname standard bid author E-R Model
  16. 16. • It represents entity sets as class and a class represents both attributes and the behavior of the entity. • Instance of a class is an object. • The internal part of the object is not externally visible. • One object communicates with the other by sending messages. Object-Oriented Model
  17. 17. • It combines the feature of relational data model and object-oriented data model. Object-Relational Model
  18. 18. • Data Definition Language(DDL): • Database language that is used to create, delete or modify database schema is called DDL. • It is used by Database Administrators(DBA) to specify the conceptual schema. • DDL interpreter converts DDL statements into equivalent low level statements understood by the DBMS. • Normally, create, alter, and drop statements are DDL statements. • DDL statements make changes in the schema Database Languages (DDL, DML)
  19. 19. Example: For create command create table Student ( sid char(4), sname varchar(50), standard integer ); DDL cont’d Example: For drop command drop Student; Example: For alter command alter table Student ADD COLUMN address varchar(20) ;
  20. 20. • Database language that enables insert, update, delete, and retrieval of data from the database is called Data Manipulation Language. • DML complier converts DML statements into equivalent low level statements that the database understands. • Normally, insert, update, delete, select are DML commands. • DML reflects change in the instance, not the schema DML
  21. 21. Example: For insert Insert into Student values(“A-101”, “Ramesh”, 12); Example: for update Update Student Set class = 11 Where sid = “A-101” ; Example: For delete DML cont’d Example: for select Select * From Student Delete from standard Where sname = “Kriti” Note: In SQL, cases are insensitive. So, instead of Student one can write StUdEnT as well. Also, for integer values “12” is incorrect but 12 is correct. And, for char and varchar “Kriti” is correct and Kriti is incorrect.
  22. 22. • Users are distinguished by the way they interact with the database system. 1. Naïve users: • They interact with the system by invoking one of the application programs written previously. Naive users are bank teller, receptionist, etc. • For e.g., bank teller needs to add Rs.90 to account Ram, and deduct the same amount from account Sita. Then the application program the bank teller uses is transfer. Database users and administrators
  23. 23. 2. Application programmers: They are specializes computer professionals who write the application programs for naïve users and for easy user interface can use an tools. 3. Sophisticated users: They make request to the database with writing application programs. 4. Specialized users: They are experts who write database application like system storing complex data types, CAD systems that do not fit to the traditional data-processing framework. Database users and administrators cont’d
  24. 24. Database administrators: DBA is a person who has control over data and the associated application programs. He is the one who can define schema, install new software, enforcing security to the system, etc. Major responsibilities of DBA are: 1. Define schema and modify as per needed 2. Install new software for efficient operations 3. Enforcing and monitoring security 4. Analyzing the data stored in the DBMS 5. Keeping the backup of the DBMS periodically 6. Ensuring the state of the hardware and software Database users and administrators cont’d
  25. 25. • Collection of operations that form a single logical unit of work are called transaction. • Transaction management ensures that the database system have ACID properties. A = atomicity C = consistency I = isolation D = durability Transaction Management
  26. 26. 1. Atomicity: Atomic means whole. This property ensures that the changes made to the database are wholly reflected or no change is made. But partial changes or execution are not made. 2. Consistency: The database must move from one consistent state to another after the execution of the transaction. Properties of Transaction Management (ACID property)
  27. 27. 3. Isolation: Even if many transaction may be done at the same time but isolation ensures that if transaction A and B are executing concurrently, then either A must execute first then B is executed or, B must execute first then A is executed. 4. Durability: Changes made to the database are permanent and even if the system failure occurs, that don’t lead to the erase of the transaction executed previously. Properties of Transaction Management (ACID property) cont’d
  28. 28. Database system structure
  29. 29. 1. Storage Manager 2. Disk Storage 3. Query Processor Its components are:
  30. 30. • Storage manager stores, retrieves, and updates data in the database. It translates DML statements into low level statements that the database understands • Its components are: • Authorization and integrity manager: It checks for the correctness of the constraints specified and also checks the authenticity of the users while entering the database. • Transaction manager: It ensures that the database follows the ACID property. • File manager: It is responsible to manage allocation of space on the disk storage. • Buffer manager: It is responsible for fetching data from the disk storage and to decide what data to cache in the main memory. It enables to handle data sizes which are larger than the size of the disk. 1. Storage Manager
  31. 31. • It is responsible for allocating the disk space and also for maintaining the data in the database. • Its components are: • Data files: It is the place where database is stored, • Data dictionary: It stores metadata about the schema of the database. • Indices: It provides quick access to the data items that hold particular values. 2. Disk Storage
  32. 32. • It simplifies and facilitates easy access to the data. • It translates queries written in non-procedural language, and operates the statement. • Its components are: • DDL interpreter: It interprets DDL statements into low-level language understood by the system. • DML compiler: It translates DML statements into an evaluation plan consisting low level instructions that the query evaluation engine understands. • Query evaluation engine: It executes low level statements generated by the DML compiler. 3. Query Processor
  33. 33. • In two tier architecture, user interface and application programs are on the client side and query and transaction facility are on the server side • When DBMS access is required, the application program establishes connection with client and server • Client queries and server provides response to the authenticated client request/queries. • There is direct interaction of client with the server • The business logic coupled with either client side or the server side. Two-tier architecture
  34. 34. Two Tier architecture
  35. 35. ADVANTAGES DISADVANTAGES • Suitable for environments where business rules do not change frequently • number of users are limited Advantages Disadvantages • Useless for large scale organizations • Only a limited number of clients can access
  36. 36. • In three tier architecture, user interface and application programs are on the client side and query and transaction facility are on the server side and in between there is an intermediate layer which stores business rules(procedures/constraints) used to access data from the database. • When DBMS access is required, the application program establishes connection with client and server but before forwarding the request of client, application rules check the client credentials. • There is indirect interaction of client with the server but direct connection of client and application rules and application rules and the server. Three Tier Architecture
  37. 37. Three Tier Architecture
  38. 38. ADVANTAGES DISADVANTAGES • Efficiency • Security • Scalability • Flexible Advantages Disadvantages • More complex structure • More difficult to setup and maintain • Expensive
  39. 39. • Instance: The collection of information currently stored in the database at the particular period. • Schema: The overall design of the database that is not expected to change frequently. • Mapping: • Metadata: Data about data. • Data dictionary: A special file that stores metadata. • Methods: Values and bodies of codes that the object contains. Common terms used in DBMS

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