Database QueriesWho murdered the database with the candlestick in the conservatory?
Fluency with Information Technology
INFO100 and CSE100
Katherine Deibel
2012-05-23 Katherine Deibel, Fluency in Information Technology 1
Review We have so far discussed
What a database is What database operations do
Today, we will discuss Databases as tools How queries are used
2012-05-23 Katherine Deibel, Fluency in Information Technology 2
Why use a database? Keep records of our:
Clients Staff Volunteers
Keep a record of activities and interventions Keep sales records Develop reports Perform research Longitudinal tracking
2012-05-23 Katherine Deibel, Fluency in Information Technology 3
Database Terminology Field (columns in a table)
Smallest unit of information in a tableSometime called “attributes”
Record(rows in a table)
All related fields are collectively called a record
Table A collection of records is a data table
Database ManagementSystem (DBMS)
All the related tables, queries, data entry and edit forms, reports, macros and VBA modules that constitute a database
2012-05-23 Katherine Deibel, Fluency in Information Technology 4
Fields (columns)
Records
(rows)
Anderson Thomas A 123 Marine Dr 237-1234Benson Karen C 1300 Ohio Ave 237-8912Casserly Rick J 12492 Rt 146 238-9011Drummond Lynn M 1209 15th Ave N 931-4545
Table
Database Terminology Field (columns in a table)
Smallest unit of information in a tableSometime called “attributes”
Record(rows in a table)
All related fields are collectively called a record
Table A collection of records is a data table
Database ManagementSystem (DBMS)
All the related tables, queries, data entry and edit forms, reports, macros and VBA modules that constitute a database
2012-05-23 Katherine Deibel, Fluency in Information Technology 5
Fields (columns)
Records
(rows)
Anderson Thomas A 123 Marine Dr 237-1234Benson Karen C 1300 Ohio Ave 237-8912Casserly Rick J 12492 Rt 146 238-9011Drummond Lynn M 1209 15th Ave N 931-4545
Table
Data | Information | Knowledge Data (according to Information Science)
Unprocessed, raw information Information
Organized, structured data that is communicated in a coherent and meaningful manner
Knowledge Information that has been evaluated and further
organized so that it can be used purposefully Action
Applying knowledge towards achieving goals
2012-05-23 Katherine Deibel, Fluency in Information Technology 6
From Data to Action We collect data Information is harvested from the data
Many companies are good at collecting data Fewer are good at harvesting information
Knowledge is elicited from the information and put into action Database Management Systems are tools for
supporting this transformation process
2012-05-23 Katherine Deibel, Fluency in Information Technology 7
Data Information Knowledge Action
Database Management Systems (DMSs)The Tools for Data to Information to Knowledge to Action
2012-05-23 Katherine Deibel, Fluency in Information Technology 8
Database Management Systems DMSs are software data tools to:
Store (tables) Organize (sort) Add, modify or delete Ask questions (queries) Produce forms and reports
Toolbox is a good analogy
2012-05-23 Katherine Deibel, Fluency in Information Technology 9
Popular DBMs Microsoft Access FileMaker Pro Lotus Notes Structured Query Language (SQL)
Microsoft SQL Server Oracle MySQL
2012-05-23 Katherine Deibel, Fluency in Information Technology 10
Managing a Database Three major distinctions
Purpose of database:Operational versus Analytical
Data representation:Flat-file versus Relational
Implementation:Desktop versus Client/Server
2012-05-23 Katherine Deibel, Fluency in Information Technology 11
Selecting a DBM Desktop databases
Oriented toward single-user applications Reside on standard personal computers
Client / Server databases Contain mechanisms to ensure the reliability and
consistency of data Offers security options on [subsets of] data Oriented toward multi-user applications
2012-05-23 Katherine Deibel, Fluency in Information Technology 12
Operational vs. AnalyticalOperational databases Used to track and assist in
daily “business” activities Data typically changes
frequently over time Examples
Human resources Mailing lists Inventory management Accounting systems Point of sale systems
(cash registers)
Analytical databases Tend to be more static Historical data is analyzed
for patterns or trends Often support the strategic
activities of an organization Goals may include
Predicting the future Summarizing historical data Prove historical assumptions
2012-05-23 Katherine Deibel, Fluency in Information Technology 13
Flat-File vs. RelationalFlat-File Database All relevant data in a
single table, or series of unrelated tables
Work best for small quantities of data
Typically a person’s first databases
Relational Database Solution to data entry
redundancy problems Tables linked together
queried as if one table Linked via common
fields (columns) with exactly the same data
2012-05-23 Katherine Deibel, Fluency in Information Technology 14
Flat-File Example Weaknesses common to flat-file systems
Duplicate information is repeated redundantly Inconsistencies in how data is entered
2012-05-23 Katherine Deibel, Fluency in Information Technology 15
Relational Database Example
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Database Tables
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Interfacing with a Relational DatabaseOur quarry is the query
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Katherine Deibel, Fluency in Information Technology 19
Accessing Data in a Database Users rarely work with the entire database
Exception are the database managers Instead, users interact through
Forms: read and write data Reports: read only
All of these are based on the query
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Forms Forms allow interaction with the database
in a more scripted fashion Data is read
and maybe even edited
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Reports Reports are summaries generated
from the database Read-only
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Katherine Deibel, Fluency in Information Technology 22
Queries Generate a table from other tables in the
database via sequences of operations Select Difference Project Product Union Join
SQL: Structured Query Language Standard database language
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Indirect SQLSQL sequences are usually auto-generated
Interfaces allow easy construction of SQL We can view the generated SQL if we want
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Query from Two Tables
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Nature of the Returned Table Some records may be editable
If the data is linked to a primary key Generally not true for collapsed data
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When fields are editable Relies on primary keys and the underlying
intelligence of the database Further security settings can set edit rights
Updates can be sent out to all views Synchronization is a big issue Editing a linked value will chance all instances
2012-05-23 Katherine Deibel, Fluency in Information Technology 26
Global Update Example Expanded database from Lab 10
2012-05-23 Katherine Deibel, Fluency in Information Technology 27
Consistency Matters A good relational database
Uses IDs to connect records across tables (i.e. relationships)
Provides specific views to meet specific users' needs
Learning these skills is beyond the scope of this course Knowing the essential ideas is part of being
fluent in databases We will discuss some basic design on Friday
2012-05-23 Katherine Deibel, Fluency in Information Technology 28
Summary Queries, on the high-level, are the
final outcome of transforming data into action
Database Management Systems provide tools for creating and manipulating queries
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Project 3 You will get to explore a database by
playing different roles at an interstellar travel agency Astronomical cartographer Trip planner Planetary information broker End consumer
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