ch1 - Chapter1:Introduction ,5thEd...

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Database System Concepts, 5th Ed . ©Silberschatz, Korth and Sudarshan See www.db-book.com for conditions on re-use Chapter 1: Introduction Chapter 1: Introduction
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©Silberschatz, Korth and Sudarshan 1.2 Database System Concepts, 5 th Ed. Chapter 1: Introduction Chapter 1: Introduction Purpose of Database Systems View of Data Database Languages Relational Databases Database Design Object-based and semi-structured databases Data Storage and Querying Transaction Management Database Architecture Database Users and Administrators Overall Structure
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©Silberschatz, Korth and Sudarshan 1.3 Database System Concepts, 5 th Ed. Database Management System (DBMS) Database Management System (DBMS) Collection of interrelated data Set of programs to access the data DBMS contains information about a particular enterprise DBMS provides an environment that is both convenient and efficient to use. Database Applications: Banking: all transactions Airlines: reservations, schedules Universities: registration, grades Sales: customers, products, purchases Manufacturing: production, inventory, orders, supply chain Human resources: employee records, salaries, tax deductions Databases touch all aspects of our lives
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©Silberschatz, Korth and Sudarshan 1.4 Database System Concepts, 5 th Ed. Purpose of Database System Purpose of Database System In the early days, database applications were built on top of file systems Drawbacks of using file systems to store data: 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
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©Silberschatz, Korth and Sudarshan 1.5 Database System Concepts, 5 th Ed. Purpose of Database Systems (Cont.) Purpose of Database Systems (Cont.) Drawbacks of using file systems (cont.) 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 Database systems offer solutions to all the above problems
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©Silberschatz, Korth and Sudarshan 1.6 Database System Concepts, 5 th Ed. Levels of Abstraction
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This note was uploaded on 09/03/2008 for the course CSE 241 taught by Professor Hillman during the Spring '08 term at Lehigh University .

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ch1 - Chapter1:Introduction ,5thEd...

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