Intro to Info Tech Database Management Systems This

Objectives n Explain u Data as a resource u Basic DB concepts F Files,

The Evolving Value of Data n Increase efficiency n Business requirement n Added value

Good Information Qualities n Accurate n Timely and accessible n Organized for need 4

Why Databases? n Before DB there were files u Finance created customer file u Marketing, shipping, etc. n Results in u Poor accessibility: files on different computers F Marketing updates don't update finance and shipping data u Duplicate data between files F Extra Copyright 2015 by Janson Industries space F Longer to update F Greater chance of error 5

Database n n n A structure that organizes data into more efficient groups DB consists of related groups of data Ex. create common Customer file and relate Marketing, Finance & Ship files 6 Copyright 2015 by Janson Industries

Databases n n Different DB types call these groups different things u File Relation Table u Record Tuple Row u Field Attribute Column DB types u Hierarchical u Relational u Object-oriented n But all duplicate functions of others 7 Copyright 2015 by Janson Industries

The Data Hierarchy n Field/Column u Has a unique name, size, and type n Record/Row n File/Table n Database n Keys u Primary – ids each record u Composite u Foreign – relates tables Copyright 2015 by Janson Industries 8

DBMS n Allows users to u. Define fields u. Group into records u. Define keys u. Relate tables/files u. Insert, change, and delete records of data n Also provides u. Data integrity u. Security Copyright 2015 by Janson Industries 9

Table Relationships n Defined by the relationship's u Number u Direction n of access The number of the relationship u For a record in one table are there one or many related records in the other table u 1: 1, 1: M, M: M n The direction of access u Unidirectional, Copyright 2015 by Janson Industries Bidirectional 10

DBMS n When a record is deleted not really deleted u Marked n for deletion – why? Data integrity: validating u When data entered, best time to validate F Range – month, day, gpa F Correct type entered – four vs. 4 F Consistent – customer id in DB F Complete – zip code 11 Copyright 2015 by Janson Industries

Other DBMS Functions n Query: retrieve and organize data u Language: SQL u GUI:

Other DBMS Functions n Backup u Can n define a schedule Recovery u Transaction n journaling Security u Restrict access by DB, individual files, records or fields by user id u Essentially creating alternative views of the data 13 Copyright 2015 by Janson Industries

DBMS Software n Lots of vendors u Software companies that create and sell DBMSs

DB Administration n DB Analyst (DA) designs DB u Interviews users u Defines fields & groups into tables u Defines keys & table relationships n DB Administrator (DBA) implements and maintains DB u Uses DBMS to create DB u Monitors performance u Insures backup and recovery 15 Copyright 2015 by Janson Industries

Points to Remember n DB at the heart of all large apps u Grocery n n checkout, Google, ATMs DB fails, application fails Variety of DB types and many DBMS vendors DBMS provides functions to create, monitor, and protect DB DBA and DA paid well 16 Copyright 2015 by Janson Industries