Introduction to Database Management Systems

Information Instructor: Csilla Farkas Office: Swearingen 3A43 Office Hours: M,T,W,Th,F 2:30 pm – 3:30 pm, electronically, or by appointment Telephone: Class homepage: /csce520.htmhttp:// 2015/csce520.htm FarkasCSCE 5202

Prerequisite CSCE 245 (CSCE 240, EECE 352) or GEOG 563 or Permission of the instructor FarkasCSCE 5203

Text books J. D. Ullman and J. Widom: A First Course in Database Systems, 3 rd edition, Prentice Hall, ISBN: X FarkasCSCE 5204

Grading Tests: Test 1: 20%, Test 2: 20%, Test3: 30% Homework Assignments: 30% Total score: 100 Final grade: 90 < A, 87 < B+ <=90, 80< B <= 87, 77 < C+ <= 80, 65 < C <= 77, 62 < D+ <= 65, 50 < D <= 62, F <= 50 FarkasCSCE 5205

Course Policies Code of Student Academic Responsibility Incompletes FarkasCSCE 5206

Questions?

Chapter 1: Introduction Evolution of Database Management Systems Overview of Database Management Systems Database-System Design FarkasCSCE 5208

Database Management System (DBMS) Databases touch all aspects of our lives DBMS: – Collection of interrelated data – Set of programs to access the data Convenient and efficient processing of data Database Applications FarkasCSCE 5209

Evolution of Database Systems Early days: database applications built on top of file systems Drawbacks of using file systems to store data: – Data redundancy and inconsistency – Difficulty in accessing data – Atomicity of updates – Concurrency control – Security – Data isolation — multiple files and formats – Integrity problems FarkasCSCE 52010

Abstraction View level: application programs hide details of data types. Logical level: What is the data? type employee = record name : string; address : string; salary: real; end; Physical level: How the data is stored? FarkasCSCE 52011

Data Models A collection of tools for describing – Data – Relationships among data items – Semantics of stored data – Database constraints FarkasCSCE 52012

Data Models Entity-Relationship model Relational model Other models: – Network – Hierarchical – Object-oriented – Semi-structured – Steaming data FarkasCSCE 52013

Database Management Systems Smaller and smaller systems – Past: large and expensive DBMS – Present: DBMS in most personal computers More and more data stored – Past: few MB – Present: terabyte (10 12 bytes), petabyte (10 15 bytes) FarkasCSCE Data Tsunami

Database Users Users are differentiated by the way they interact with the system Database Administration: responsible for the structure or schema of the database (DDL), coordinates all activities regarding the database Application programmers – interact with system through DML calls Sophisticated users – form requests in a database query language Naive users – invoke one of the permanent application programs that have been written previously FarkasCSCE 52015

Data Definition Language (DDL) Defines the database schema and constraints DDL compiler  data dictionary Metadata – data about data FarkasCSCE 52016

Data Manipulation Language (DML) Accessing and manipulating the data – DML – query language Query 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 SQL: nonprocedural query language FarkasCSCE 52017

Transaction Management Transaction: unit of work to be executed atomically and in isolation from other transactions Transaction-manager: ensures that the database remains in a consistent – system failures – transaction failures Concurrency-control: interaction among the concurrent transactions to ensure consistency FarkasCSCE 52018

ACID Properties Atomicity: all-or-nothing of the transaction’s effect will take place Consistency: each transaction leaves the system in a consistent state Isolation: each transaction must appear to be executed as if no other transactions are executed at the same time Durability: effect of a transaction must never be lost after the transaction is completed FarkasCSCE 52019

Transaction Processing Logging: – Log manager – Recovery manager Concurrency control – Multiple transactions – Locking protocols Deadlock resolution FarkasCSCE 52020

Database System Studies Design of the database – What to store, structure, semantics – Functionality requirement – Trade offs – Security Database programming – How to express database operations, capability requirements, etc. Database implementation – Query, transaction processing, storage, efficiency FarkasCSCE 52021

Next Class: Relational Database Modeling A First Course: Chapter 2 (2.1, 2.2, 2.3) FarkasCSCE 52022