Databases and Database Users Winter 2007Ron McFadyen ACS Database applications Database Database Management System Characteristics Actors Advantages Implications When not to use a DBMS Ch 1

Databases and Database Users Winter 2007Ron McFadyen ACS Database applications traditional multimedia - pictures, video, sound scientific databases - GIS: maps, weather, satellite images - biological database: DNA sequence analysis warehouse, OLAP - analysis, decision making real-time, active databases - industrial processes deductive databases - combination of inference and databases Our focus

Databases and Database Users Winter 2007Ron McFadyen ACS Database collection of related data represents some aspect of the real world logically coherent collection built with a specific purpose in mind could be anywhere - notebook, spreadsheet, Access, Oracle, … could be manual / could be computerized Data known and recordable facts - meaningful name, phone number, address, grade,...

Databases and Database Users Winter 2007Ron McFadyen ACS Database Management System (DBMS) collection of software facilitating the definition, construction and manipulation of databases Users/ actors Request manager Storage manager Meta data Stored database DBMS Applications / Queries

Databases and Database Users Winter 2007Ron McFadyen ACS Database Management System (DBMS) Definition (design), construction, manipulation Definition record structure data elements names data types constraints etc Construction create database files populate the database with records Manipulation querying updating

Databases and Database Users Winter 2007Ron McFadyen ACS Sample database - structure CNameCNoCrHrsDept Course Student NameStNoClassMajor GradeReport StNoSidGrade Section SIdCNoSemesterYearInstructor PreCNoCNo Prerequisite We must define each structure name / location attribute names attribute data types

Databases and Database Users Winter 2007Ron McFadyen ACS Sample database - rows Student Name StNo Class Major Smith 17 1 CS Brown 8 2 CS Course CName CNo CrHrs Dept Database CS C CS Section SId CNo Semester Year Instructor Spring 2000 Smith Winter 2000 Smith Spring 2000 Jones GradeReport StNo Sid Grade A B

Databases and Database Users Winter 2007Ron McFadyen ACS Characteristics of the Database approach single repository of data sharable by multiple users concurrency control transaction control OLTP self-describing - system catalogue contains meta data program-data independence some changes to the database are transparent to programs/users multiple views of data - to support individual needs of programs/users

Databases and Database Users Winter 2007Ron McFadyen ACS Database Actors Database Administrator (DBA) -authorizing access to the database -coordinating and monitoring its use -acquiring software and hardware as needed -solving problems such as breach of security or poor system performance Database Designers/Modelers -identifying the data to be stored -choosing appropriate data structure End-users -access to the database: querying, updating, generating reports Software Engineers -developing application programs

Databases and Database Users Winter 2007Ron McFadyen ACS Advantages of the Database approach (capabilities we would look for in a DBMS) controlled redundancy persistent storage efficient execution of queries multiple user interfaces representation of complex relationships controlled/authorized access to data enforcing integrity constraints backup and recovery

Databases and Database Users Winter 2007Ron McFadyen ACS Implications of the Database approach standards enforcement DBA can enforce standard naming conventions, etc reduced application development time adding new functionality to an existing database is “easy” flexibility adding new data and making some types of changes is “easy” up-to-date information - due to sharable characteristic economies of scale - due to sharable resources the whole organization can make one investment

Databases and Database Users Winter 2007Ron McFadyen ACS When not to use a DBMS overhead costs are too great high initial investment generality overhead of security, concurrency control, recovery, integrity data and applications are simple, well-defined, not expected to change stringent real-time constraints multi-user environment not needed