0001 introduction to database management system
- 1. http://tutorials.algaeservice.com/ 1http://tutorials.algaeservice.com/ www.algaeservices.co.in Module 1 RDBMS & Data Warehousing Chapter 1: Introduction to Database Management System By: Algae Services Email: [email protected] Course: http://tutorials.algaeservice.com/
- 2. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ About Us Author: Algae Services Have Decade of experience in Corporate Training Classroom sessions in different streams of Technology. • Expertise in Big Data, ERP, Business Process Engineering, Database Technologies, Spread sheet modeling. • Worked with top service and product companies like Wipro , Volvo , TVS , TEG ANALYTICS, General Electrics , Royal Bank of Scotland , Verizon etc. • Worked with Universities like Jain University , RGTU, Praxis, LMS Pro-School. www.algaeservices.co.in2
- 3. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ What is Database • A Database is a collection of related data organized in a way that data can be easily accessed, managed and updated. • Any piece of information can be a data Example name of your school. • Database is actually a place where related piece of information is stored and various operations can be performed on it. www.algaeservices.co.in
- 4. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ What is DBMS • A DBMS is a software that allows creation, definition and manipulation of database. • DBMS is actually a tool used to perform any kind of operation on data in database. • DBMS also provides protection and security to database. • It maintains data consistency in case of multiple users. Examples: • MySql • Oracle • Sybase • Microsoft Access • IBM DB2 www.algaeservices.co.in
- 5. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ Historical Perspective Early 1960s Integrated data store, first general-purpose DBMS designed by Charles Bachman at GE Formed basis for network data model later Bachman received Turing Award in 1973 for his work in database area Late 1960s IBM developed Information Management System (IMS), used even today in many major installations IMS formed the basis for hierarchical data model American Airlines and IBM jointly developed SABRE for making airline reservations 1970 Edgar Codd, at IBM’s San Jose Research Laboratory, proposed relational data model. It sparked the rapid development of several DBMSs based on relational model, along with a rich body of theoretical results that placed the field on a firm foundation. Codd won 1981 Turing Award. Database systems matured as an academic discipline The benefits of DBMS were widely recognized, and the use of DBMSs for managing corporate data became standard practice. www.algaeservices.co.in
- 6. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ Historical Perspective (Cont.) 1980s Relational data model consolidated its position as dominant DBMS paradigm, and database systems continued to gain widespread use SQL query language, developed as part of IBM’s System R project, is now the standard query language SQL was standardized in late 1980s, and current standard SQL:1999 was adopted by ANSI and ISO Late 1980s till 1990s Considerable research into more powerful query language and richer data model, with emphasis on supporting complex analysis of data from all parts of an enterprise Several vendors, e.g., IBM’s DB2, Oracle 8, Informix UDS, extended their systems with the ability to store new data types such as images and text, and to ask more complex queries Data warehouses have been developed by many vendors to consolidate data from several databases, and for carrying out specialized analysis www.algaeservices.co.in
- 7. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ DBMS Data Model • A Database model defines the logical design of data. • The model describes the relationships between different parts of the data. • Historically, in database design, three models are commonly used. They are, 1. Hierarchical Model 2. Network Model 3. Relational Model www.algaeservices.co.in
- 8. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ Hierarchical Model • In this model each entity has only one parent but can have several children . At the top of hierarchy there is only one entity which is called Root. www.algaeservices.co.in
- 9. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ Network Model • The network database model was invented by Charles Bachman in 1969 as an enhancement of the already existing database model, the hierarchical database model. • Because the hierarchical database model was highly flaw, Bachman decided to create a database that is similar to the hierarchical database but with more flexibility and less defaults. • The original and existing hierarchical database has one owner file linked strictly to one member file, creating a ladder affect that restricted the database to find relationships outside of its category. • In the network model, entities are organized in a graph, in which some entities can be accessed through several path www.algaeservices.co.in
- 10. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ Software's using Network Model • Integrated Data Store (IDS) • IDMS (Integrated Database Management System) • RDM Embedded • RDM Server • Turbo IMAGE • Univac DMS-1100 www.algaeservices.co.in
- 11. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ Structured vs. Unstructured Data High maintenance costs Data Redundancy: The same data will be represented multiple times in the file Data dependence: If you change things about the file format then there will be expensive changes to programs that use it Ensuring data consistency and controlling access to the data is difficult (i.e. you cannot finely control multi-user access to the file) THE PROBLEM WITH UNSTRUCTURED DATA Flat file = unstructured data Database = structured data www.algaeservices.co.in
- 12. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ Advantages and Disadvantages of Network Model • Advantages of a Network Database Model 1. Because it has the many-many relationship, network database model can easily be accessed in any table record in the database 2. For more complex data, it is easier to use because of the multiple relationship founded among its data 3. Easier to navigate and search for information because of its flexibility • Disadvantage of a Network Database Model 1. Difficult for first time users 2. Difficulties with alterations of the database because when information entered can alter the entire database www.algaeservices.co.in
- 13. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ Difference Between Network and Hierarchical models # Network Database Model Hierarchical Database Model 1 Many-to-many relationship One-to-many relationship 2 Easily accessed because of the linkage between the information Difficult to navigate because of its strict owner to member connection 3 Great flexibility among the information files because the multiple relationships among the files Less flexibility with the collection of information because of the hierarchical position of the files www.algaeservices.co.in
- 14. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ Relational Model • In this model, data is organised in two-dimesional tables called relations. The tables or relation are related to each other. www.algaeservices.co.in
- 15. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ What is RDBMS • RDBMS stands for Relational Database Management Systems • It is called Relational Data Base Management System (RDBMS) because it is based on relational model introduced by E.F. Codd. • In RDBMS data is represented in terms of tuples (rows). • Due to a collection of organized set of tables, data can be accessed easily in RDBMS. • Relational database is most commonly used database. • It contains number of tables and each table has its own primary key. www.algaeservices.co.in
- 16. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ RDBMS SAMPLE TABLE www.algaeservices.co.in City State High Low Bangalore Karnataka 105 90 Mumbai Maharastra 101 92 Chennai Tamil nadu 88 69 New Delhi Delhi 77 60 Kashmir Jammu & Kashmir 80 60
- 17. http://tutorials.algaeservice.com/ LEVELS OF ABSTRACTION Abstraction means hide all but the relevant data about an object in order to reduce complexity and increase efficiency. Three types of abstraction Physical level: describes how a record (e.g., customer) is stored. Logical level: describes data stored in database, and the relationships among the data. type customer = record name : string; street : string; city : integer; end; View level: application programs hide details of data types. Views can also hide information (e.g., salary) for security purposes. www.algaeservices.co.in
- 18. http://tutorials.algaeservice.com/ VIEW OF DATA An architecture for a database system www.algaeservices.co.in
- 19. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ Difference Between DBMS and RDBMS # DBMS RDBMS 1) DBMS applications store data as file. RDBMS applications store data in a tabular form. 2) In DBMS, data is generally stored in either a hierarchical form or a navigational form. In RDBMS, the tables have an identifier called primary key and the data values are stored in the form of tables. 3) Normalization is not present in DBMS. Normalization is present in RDBMS. 4) DBMS does not apply any security with regards to data manipulation. RDBMS defines the integrity constraint for the purpose of ACID (Atomocity, Consistency, Isolation and Durability) property. 5) DBMS uses file system to store data, so there will be no relation between the tables. in RDBMS, data values are stored in the form of tables, so a relationship between these data values will be stored in the form of a table as well. 6) DBMS has to provide some uniform methods to access the stored information. RDBMS system supports a tabular structure of the data and a relationship between them to access the stored information. 7) DBMS does not support distributed database. RDBMS supports distributed database. 8) DBMS is meant to be for small organization and deal with small data. it supports single user. RDBMS is designed to handle large amount of data. it supports multiple users. 9) Examples of DBMS are file systems, xml etc. Example of RDBMS are mysql, postgre, sql server, oracle etc. www.algaeservices.co.in
- 20. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ Drawbacks of using file systems In the early days, database applications were built on top of file systems but there were lot of drawbacks Data redundancy and inconsistency Multiple file formats, duplication of information in different files Difficulty in accessing data Need to write a new program to carry out each new task Data isolation — multiple files and formats Integrity problems Integrity constraints (e.g. account balance > 0) become part of program code Hard to add new constraints or change existing ones Atomicity of updates Failures may leave database in an inconsistent state with partial updates carried out E.g. transfer of funds from one account to another should either complete or not happen at all Concurrent access by multiple users Concurrent accessed needed for performance Uncontrolled concurrent accesses can lead to inconsistencies E.g. two people reading a balance and updating it at the same time Security problems www.algaeservices.co.in
- 21. http://tutorials.algaeservice.com/ SCHEMAS Similar to types and variables in programming languages Schema – the logical structure of the database e.g., the database consists of information about a set of customers and accounts and the relationship between them) Analogous to type information of a variable in a program Physical schema: database design at the physical level Logical schema: database design at the logical level www.algaeservices.co.in
- 22. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ Why is the data model so important? • We generally settle for a design that “does the job” even though we recognize that with more time and effort we might be able to develop a more elegant solution. • Reasons: – LEVERAGE • A small change in the data model may have a major impact on the system as a whole. • Programs and applications using the database are heavily influenced by the database design (i.e. the data model). • A well-designed data model can make the development of programs and applications simpler and easier. • Poor data organization can be very expensive to fix. – CONCISENESS • A data model is a very powerful tool for expressing the heart of the information systems requirements and capabilities. – DATA QUALITY • Data held in a database is almost always a valuable asset that is built up over time. • Poor data quality (inaccurate data) reduces the asset value and can be expensive or impossible to correct. • The data model is important in achieving good data quality because it defines www.algaeservices.co.in
- 23. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ • How does this model support the sound overall system design and meets the business requirements? – COMPLETENESS • Does the model support all the necessary data? – NONREDUNDANCY • Does the model specify a database in which the same fact could be recorded more than once? – ENFORCEMENT OF BUSINESS RULES – DATA REUSABILITY • Will the data stored in the database be reusable for purposes beyond those anticipated in the present process model? • If data has been organized with one particular application in mind, it is often difficult to use for other purposes. – STABILITY AND FLEXIBILITY • How well will the model cope with possible changes to the business requirements? • A data model is stable when, in the face of change to requirements, we do not need to modify it. • A data model is flexible when it can be readily extended to accommodate new requirements with minimal impact on the existing structure. – ELEGANCE • Does the data model provide a reasonably neat and simple classification of the data? – COMMUNICATION • Does the data model represent the concepts that the users who are familiar with it and can easily verify? • Will programmers interpret the model correctly? – INTEGRATION • How will the database fit into the organization’s existing databases? How many other databases hold similar data? WHAT MAKES A GOOD DATA MODEL? (CONT’D) www.algaeservices.co.in
- 24. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ Performance • Why is performance not in the list of quality criteria? – Performance differs from our other criteria because it depends heavily on the software and hardware platforms on which the database will run. – Exploiting the capabilities of the hardware and software is a technical task quite different from the modeling activity. – The usual and recommended procedure is to develop the data model without considering performance, then attempt to implement it with the available hardware and software. www.algaeservices.co.in
- 25. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ Data Definition Language (DDL) • Specification notation for defining the database schema – E.g. create table account ( account-number char(10), balance integer) • DDL compiler generates a set of tables stored in a data dictionary • Data dictionary contains metadata (i.e., data about data) – Database schema – Data storage and definition language • Language in which the storage structure and access methods used by the database system are specified • Usually an extension of the data definition language • Commands – CREATE TABLE – CREATE INDEX – ALTER TABLE – RENAME TABLE – DROP TABLE – DROP INDEX www.algaeservices.co.in
- 26. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ Data Manipulation Language (DML) • Language for accessing and manipulating the data organized by the appropriate data model – DML also known as query language • Two classes of languages – Procedural – user specifies what data is required and how to get those data – Nonprocedural – user specifies what data is required without specifying how to get those data – Commands – SELECT - Retrieve data from the a database – INSERT - Insert data into a table – UPDATE - Updates existing data within a table – DELETE - deletes all records from a table, the space for the records remain www.algaeservices.co.in
- 27. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ SQL • SQL: widely used non-procedural language – E.g. find the name of the customer with customer-id 192-83-7465 select customer.customer-name from customer where customer.customer-id = ‘192-83-7465’ – E.g. find the balances of all accounts held by the customer with customer-id 192-83-7465 select account.balance from depositor, account where depositor.customer-id = ‘192-83-7465’ and depositor.account-number = account.account-number • Application programs generally access databases through one of – Language extensions to allow embedded SQL – Application program interface (e.g. ODBC/JDBC) which allow SQL queries to be sent to a database www.algaeservices.co.in
- 28. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ Database Users • Users are differentiated by the way they expect to interact with the system • Application programmers – interact with system through DML calls • Sophisticated users – form requests in a database query language • Specialized users – write specialized database applications that do not fit into the traditional data processing framework • Naïve users – invoke one of the permanent application programs that have been written previously – E.g. people accessing database over the web, bank tellers, clerical staff www.algaeservices.co.in
- 29. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ Database Administrator • Coordinates all the activities of the database system; the database administrator has a good understanding of the enterprise’s information resources and needs. • Database administrator's duties include: – Schema definition – Storage structure and access method definition – Schema and physical organization modification – Granting user authority to access the database – Specifying integrity constraints – Acting as liaison with users – Monitoring performance and responding to changes in requirements www.algaeservices.co.in
- 31. http://tutorials.algaeservice.com/ Application Architectures Two-tier architecture: E.g. client programs using ODBC/JDBC to communicate with a database Three-tier architecture: E.g. web-based applications, and applications built using “middleware” www.algaeservices.co.in
- 32. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ About Us Author: Algae Services Have Decade of experience in Corporate Training Classroom sessions in different streams of Technology. • Expertise in Big Data, ERP, Business Process Engineering, Database Technologies, Spread sheet modeling. • Worked with top service and product companies like Wipro , Volvo , TVS , TEG ANALYTICS, General Electrics , Royal Bank of Scotland , Verizon etc. • Worked with Universities like Jain University , RGTU, Praxis, LMS Pro-School. www.algaeservices.co.in
- 33. http://tutorials.algaeservice.com/http://tutorials.algaeservice.com/ Contact Us – Thanks – Algae Services – www.algaeservices.co.in – http://tutorials.algaeservice.com/ – BTM Bangalore www.algaeservices.co.in