Transcript Using Databases to Manage Information

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