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Using Databases to Manage Information Chapter 8 – Computers: Understanding Technology Definitions • Database - computerized system for storing information so that information can be searched for and retrieved when needed • Field – smallest data category in a database • Record – collection of fields describing relating to an entity (person, place, thing, or event) • 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 Student 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 that are related to each other in such a way that there isn’t duplication – information stored in only one place 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 Database Operations • • • • • Adding records Modifying records Deleting records Sorting records Indexing records – index makes retrieval quicker