Chapter 1: Introduction        Database System Concepts, 1 st Ed.©VNS InfoSolutions Private Limited, Varanasi(UP), India 2...
Chapter 1: Introduction             s Purpose of Database Systems             s View of Data             s Database Langua...
Database Management System                                (DBMS)            s DBMS contains information about a particular...
Purpose of Database Systems            s In the early days, database applications were built directly on top of           ...
Purpose of Database Systems                                  (Cont.)            s Drawbacks of using file systems (cont.) ...
Levels of Abstraction            s Physical level: describes how a record (e.g., customer) is stored.            s Logical...
View of Data           An architecture for a database systemDatabase System Concepts – 1 st Ed         1.7   ©VNS InfoSolu...
Instances and Schemas            s    Similar to types and variables in programming languages            s    Schema – the...
Data Models             s A collection of tools for describing                   q Data                   q Data relations...
Data Manipulation Language (DML)            s Language for accessing and manipulating the data organized by the           ...
Data Definition Language (DDL)            s Specification notation for defining the database schema                  Examp...
Relational Model                                                                                            Attributes    ...
A Sample Relational DatabaseDatabase System Concepts – 1 st Ed   1.13   ©VNS InfoSolutions Private Limited, Varanasi(UP), ...
SQL            s SQL: widely used non-procedural language                   q   Example: Find the name of the customer wit...
Database Design            The process of designing the general structure of the database:            s Logical Design – D...
The Entity-Relationship Model            s Models an enterprise as a collection of entities and relationships             ...
Object-Relational Data Models             s Extend the relational data model by including object orientation and          ...
XML: Extensible Markup Language            s Defined by the WWW Consortium (W3C)            s Originally intended as a doc...
Storage Management            s Storage manager is a program module that provides the interface                 between th...
Query Processing            1. Parsing and translation            2. Optimization            3. EvaluationDatabase System ...
Query Processing (Cont.)            s Alternative ways of evaluating a given query                   q   Equivalent expres...
Transaction Management            s A transaction is a collection of operations that performs a single                 log...
Database Architecture            The architecture of a database systems is greatly influenced by             the underlyin...
Database Users            Users are differentiated by the way they expect to interact with            the system          ...
Database Administrator            s Coordinates all the activities of the database system; the                 database ad...
Overall System StructureDatabase System Concepts – 1 st Ed     1.26   ©VNS InfoSolutions Private Limited, Varanasi(UP), In...
History of Database Systems            s 1950s and early 1960s:                  q   Data processing using magnetic tapes ...
History (cont.)            s 1980s:                  q   Research relational prototypes evolve into commercial systems    ...
End of Chapter 1        Database System Concepts, 1 st Ed.©VNS InfoSolutions Private Limited, Varanasi(UP), India 221002  ...
Figure 1.4Database System Concepts – 1 st Ed      1.30   ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
Figure 1.7Database System Concepts – 1 st Ed      1.31   ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
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A great power point presentation for DBMS Concepts from start to end and with best examples chapter by chapter. Please go though each chapters sequentially for your knowledge.

A very easy going study material for better understanding and concepts of Database Management System.

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Vnsispl dbms concepts_ch1

  1. 1. Chapter 1: Introduction Database System Concepts, 1 st Ed.©VNS InfoSolutions Private Limited, Varanasi(UP), India 221002 See www.vnsispl.com for conditions on re-use
  2. 2. Chapter 1: Introduction s Purpose of Database Systems s View of Data s Database Languages s Relational Databases s Database Design s Object-based and semistructured databases s Data Storage and Querying s Transaction Management s Database Architecture s Database Users and Administrators s Overall Structure s History of Database SystemsDatabase System Concepts – 1 st Ed 1.2 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  3. 3. Database Management System (DBMS) s DBMS contains information about a particular enterprise q Collection of interrelated data q Set of programs to access the data q An environment that is both convenient and efficient to use s Database Applications: q Banking: all transactions q Airlines: reservations, schedules q Universities: registration, grades q Sales: customers, products, purchases q Online retailers: order tracking, customized recommendations q Manufacturing: production, inventory, orders, supply chain q Human resources: employee records, salaries, tax deductions s Databases touch all aspects of our livesDatabase System Concepts – 1 st Ed 1.3 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  4. 4. Purpose of Database Systems s In the early days, database applications were built directly on top of file systems s Drawbacks of using file systems to store data: q Data redundancy and inconsistency  Multiple file formats, duplication of information in different files q Difficulty in accessing data  Need to write a new program to carry out each new task q Data isolation — multiple files and formats q Integrity problems  Integrity constraints (e.g. account balance > 0) become “buried” in program code rather than being stated explicitly  Hard to add new constraints or change existing onesDatabase System Concepts – 1 st Ed 1.4 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  5. 5. Purpose of Database Systems (Cont.) s Drawbacks of using file systems (cont.) q Atomicity of updates  Failures may leave database in an inconsistent state with partial updates carried out  Example: Transfer of funds from one account to another should either complete or not happen at all q Concurrent access by multiple users  Concurrent accessed needed for performance  Uncontrolled concurrent accesses can lead to inconsistencies – Example: Two people reading a balance and updating it at the same time q Security problems  Hard to provide user access to some, but not all, data s Database systems offer solutions to all the above problemsDatabase System Concepts – 1 st Ed 1.5 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  6. 6. Levels of Abstraction s Physical level: describes how a record (e.g., customer) is stored. s Logical level: describes data stored in database, and the relationships among the data. type customer = record customer_id : string; customer_name : string; customer_street : string; customer_city : integer; end; s View level: application programs hide details of data types. Views can also hide information (such as an employee’s salary) for security purposes.Database System Concepts – 1 st Ed 1.6 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  7. 7. View of Data An architecture for a database systemDatabase System Concepts – 1 st Ed 1.7 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  8. 8. Instances and Schemas s Similar to types and variables in programming languages s Schema – the logical structure of the database q Example: The database consists of information about a set of customers and accounts and the relationship between them) q Analogous to type information of a variable in a program q Physical schema: database design at the physical level q Logical schema: database design at the logical level s Instance – the actual content of the database at a particular point in time q Analogous to the value of a variable s Physical Data Independence – the ability to modify the physical schema without changing the logical schema q Applications depend on the logical schema q In general, the interfaces between the various levels and components should be well defined so that changes in some parts do not seriously influence others.Database System Concepts – 1 st Ed 1.8 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  9. 9. Data Models s A collection of tools for describing q Data q Data relationships q Data semantics q Data constraints s Relational model s Entity-Relationship data model (mainly for database design) s Object-based data models (Object-oriented and Object-relational) s Semistructured data model (XML) s Other older models: q Network model q Hierarchical modelDatabase System Concepts – 1 st Ed 1.9 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  10. 10. Data Manipulation Language (DML) s Language for accessing and manipulating the data organized by the appropriate data model q DML also known as query language s Two classes of languages q Procedural – user specifies what data is required and how to get those data q Declarative (nonprocedural) – user specifies what data is required without specifying how to get those data s SQL is the most widely used query languageDatabase System Concepts – 1 st Ed 1.10 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  11. 11. Data Definition Language (DDL) s Specification notation for defining the database schema Example: create table account ( account-number char(10), balance integer) s DDL compiler generates a set of tables stored in a data dictionary s Data dictionary contains metadata (i.e., data about data) q Database schema q Data storage and definition language  Specifies the storage structure and access methods used q Integrity constraints  Domain constraints  Referential integrity (references constraint in SQL)  Assertions q AuthorizationDatabase System Concepts – 1 st Ed 1.11 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  12. 12. Relational Model Attributes s Example of tabular data in the relational modelDatabase System Concepts – 1 st Ed 1.12 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  13. 13. A Sample Relational DatabaseDatabase System Concepts – 1 st Ed 1.13 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  14. 14. SQL s SQL: widely used non-procedural language q Example: 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’ q Example: 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 s Application programs generally access databases through one of q Language extensions to allow embedded SQL q Application program interface (e.g., ODBC/JDBC) which allow SQL queries to be sent to a databaseDatabase System Concepts – 1 st Ed 1.14 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  15. 15. Database Design The process of designing the general structure of the database: s Logical Design – Deciding on the database schema. Database design requires that we find a “good” collection of relation schemas. q Business decision – What attributes should we record in the database? q Computer Science decision – What relation schemas should we have and how should the attributes be distributed among the various relation schemas? s Physical Design – Deciding on the physical layout of the databaseDatabase System Concepts – 1 st Ed 1.15 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  16. 16. The Entity-Relationship Model s Models an enterprise as a collection of entities and relationships q Entity: a “thing” or “object” in the enterprise that is distinguishable from other objects  Described by a set of attributes q Relationship: an association among several entities s Represented diagrammatically by an entity-relationship diagram:Database System Concepts – 1 st Ed 1.16 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  17. 17. Object-Relational Data Models s Extend the relational data model by including object orientation and constructs to deal with added data types. s Allow attributes of tuples to have complex types, including non-atomic values such as nested relations. s Preserve relational foundations, in particular the declarative access to data, while extending modeling power. s Provide upward compatibility with existing relational languages.Database System Concepts – 1 st Ed 1.17 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  18. 18. XML: Extensible Markup Language s Defined by the WWW Consortium (W3C) s Originally intended as a document markup language not a database language s The ability to specify new tags, and to create nested tag structures made XML a great way to exchange data, not just documents s XML has become the basis for all new generation data interchange formats. s A wide variety of tools is available for parsing, browsing and querying XML documents/dataDatabase System Concepts – 1 st Ed 1.18 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  19. 19. Storage Management s Storage manager is a program module that provides the interface between the low-level data stored in the database and the application programs and queries submitted to the system. s The storage manager is responsible to the following tasks: q Interaction with the file manager q Efficient storing, retrieving and updating of data s Issues: q Storage access q File organization q Indexing and hashingDatabase System Concepts – 1 st Ed 1.19 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  20. 20. Query Processing 1. Parsing and translation 2. Optimization 3. EvaluationDatabase System Concepts – 1 st Ed 1.20 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  21. 21. Query Processing (Cont.) s Alternative ways of evaluating a given query q Equivalent expressions q Different algorithms for each operation s Cost difference between a good and a bad way of evaluating a query can be enormous s Need to estimate the cost of operations q Depends critically on statistical information about relations which the database must maintain q Need to estimate statistics for intermediate results to compute cost of complex expressionsDatabase System Concepts – 1 st Ed 1.21 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  22. 22. Transaction Management s A transaction is a collection of operations that performs a single logical function in a database application s Transaction-management component ensures that the database remains in a consistent (correct) state despite system failures (e.g., power failures and operating system crashes) and transaction failures. s Concurrency-control manager controls the interaction among the concurrent transactions, to ensure the consistency of the database.Database System Concepts – 1 st Ed 1.22 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  23. 23. Database Architecture The architecture of a database systems is greatly influenced by the underlying computer system on which the database is running: s Centralized s Client-server s Parallel (multi-processor) s DistributedDatabase System Concepts – 1 st Ed 1.23 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  24. 24. Database Users Users are differentiated by the way they expect to interact with the system s Application programmers – interact with system through DML calls s Sophisticated users – form requests in a database query language s Specialized users – write specialized database applications that do not fit into the traditional data processing framework s Naï ve users – invoke one of the permanent application programs that have been written previously q Examples, people accessing database over the web, bank tellers, clerical staffDatabase System Concepts – 1 st Ed 1.24 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  25. 25. Database Administrator s Coordinates all the activities of the database system; the database administrator has a good understanding of the enterprise’s information resources and needs. s Database administrators duties include: q Schema definition q Storage structure and access method definition q Schema and physical organization modification q Granting user authority to access the database q Specifying integrity constraints q Acting as liaison with users q Monitoring performance and responding to changes in requirementsDatabase System Concepts – 1 st Ed 1.25 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  26. 26. Overall System StructureDatabase System Concepts – 1 st Ed 1.26 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  27. 27. History of Database Systems s 1950s and early 1960s: q Data processing using magnetic tapes for storage  Tapes provide only sequential access q Punched cards for input s Late 1960s and 1970s: q Hard disks allow direct access to data q Network and hierarchical data models in widespread use q Ted Codd defines the relational data model  Would win the ACM Turing Award for this work  IBM Research begins System R prototype  UC Berkeley begins Ingres prototype q High-performance (for the era) transaction processingDatabase System Concepts – 1 st Ed 1.27 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  28. 28. History (cont.) s 1980s: q Research relational prototypes evolve into commercial systems  SQL becomes industrial standard q Parallel and distributed database systems q Object-oriented database systems s 1990s: q Large decision support and data-mining applications q Large multi-terabyte data warehouses q Emergence of Web commerce s 2000s: q XML and XQuery standards q Automated database administrationDatabase System Concepts – 1 st Ed 1.28 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  29. 29. End of Chapter 1 Database System Concepts, 1 st Ed.©VNS InfoSolutions Private Limited, Varanasi(UP), India 221002 See www.vnsispl.com for conditions on re-use
  30. 30. Figure 1.4Database System Concepts – 1 st Ed 1.30 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100
  31. 31. Figure 1.7Database System Concepts – 1 st Ed 1.31 ©VNS InfoSolutions Private Limited, Varanasi(UP), India 22100

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