Database and Information Management Chapter 9 – Computers: Understanding Technology, 3 rd edition

Definitions Database - computerized system for storing information so that information can be searched for and retrieved when needed Entity – person, place, thing, or event Field – smallest data category in a database, generally has 3 attributes – data type, name, size (number of characters that can be entered) Record – collection of fields describing an entity Table – collection of records containing the same fields Primary key – For a field to be a primary key in a table, it must have a value for every record and the value must be unique (no 2 records with same value)

Queries Queries – questions to retrieve needed information from database Structured Query Language (SQL) is the most popular database query language Example: SELECT Student.FName, Student.LName, Student.StuID FROM StudentData WHERE Student.GPA>3.49 AND Student.Enrolled=“YES”

Databases Classified by Data Model Flat File Databases – contain only one table or file Relational Databases – information stored in tables related to each other so that a piece of data is stored in only one place Object-oriented Databases – data stored in objects – each object will have allowable actions (methods) associated with it

Databases Classified by Function Operational databases – working systems that are continually being updated Data warehouse – Data is extracted from the warehouse but the warehouse is typically not modified or updated with new information

Planning for a New Database Organizational structure for the data – what fields, grouping fields by table, choosing data types for fields Design a front-end user interface for the database for data entry Design reporting capabilities

Database Objects Forms – Templates which facilitate entry of data into database Reports – Formatted output from database –Data filters – report will only show some records (e.g. WHERE clause in SELECT statement) Although form and report capabilities are part of databases, increasingly web-based forms and reports are being used for the “front end” leaving the database to do the “back end”

Database Administrator Data loss or corruption Backup and recovery Database response time Record locking – simultaneous viewing is OK, but simultaneous editing is not Data Integrity – normalization aims to eliminate data redundancy Data validation – range checks, alphanumeric checks, consistency checks, completeness checks, referential integrity

Database Operations Adding records Modifying records Deleting records Sorting records Indexing records – index makes retrieval quicker