mark dixon 1 06 – jsp databases: multiple tables
TRANSCRIPT
Mark Dixon 1
06 – JSP Databases: Multiple Tables
Mark Dixon 2
Admin: Test• Next week (Mon 5th) 11:00-13:00• Individual• 40% of module mark• Open book:
Web-site: mdixon.soc.plymouth.ac.ukPrinted slidesRobbins J (2006) HTML & XHTML Pocket Reference
(3rd edition). O'Reilly. ISBN: 978-0-596-52727-3 Bergsten H (2001) JavaServer Pages Pocket
Reference. O'Reilly. ISBN: 978-0-596-00231-2Gennick J (2006) SQL Pocket Guide (2nd edition).
O'Reilly. ISBN: 978-0-596-52688-7Google
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Example: DistanceSPECIFICATION
• User Requirements – need to convert a given distance in miles to
kilometres (1 mile = 1.6 km)
• Software Requirements– Functional:
–User should be able to enter the distance (in miles)
–the distance (in kilometres) should be calculated and displayed
– Non-functionalmust use JavaScriptshould be quick and easy to use
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Example: Land Area (what)SPECIFICATION
• User Requirements – need to know the land area in acres, given the
length and width in metres (1 m = 1.09 yds)
• Software Requirements– Functional:
–User should be able to enter the length and the width (in metres)
–the length and width (in yds), and the area (in acres) should be calculated and displayed
– Non-functionalmust use JSP server-side code (not JavaScript)should be quick and easy to use
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Example: Land Area (how)• Acre – unit of measurement of land area
– long strip of land: can be ploughed in a day
• 1 Acre = 220 yds x 22 yds (= 4840 yds2)
• 1 furlong (furrow long) = 220 yds
22yds
220yds
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Example: CountriesSPECIFICATION
• User Requirements – Manage population data
• Software Requirements– Functional:
–Country List page: should list all countries in the database (each item should be a link to the Country page).
–Country page: should list all details for specific country.
– Non-functionalmust use JSP server-side code (not JavaScript)should be quick and easy to use
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Questions: Databases• How many records are in the following table?• How many fields does the following table have?
64
CountryName Population Land Mass Continent
UK 60776238 241590 EuropeSpain 40448191 499542 EuropeGermany 82400996 349223 EuropeEgypt 80335036 995450 AfricaKenya 36913721 569250 AfricaChina 1321851888 9326410 Asia
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Questions: SQL• Write an SQL statement to display the name and
land mass of all countries in Africa.
SELECT Name, Land MassFROM Country WHERE Continent = 'Africa';
CountryName Population Land Mass Continent
UK 60776238 241590 EuropeSpain 40448191 499542 EuropeGermany 82400996 349223 EuropeEgypt 80335036 995450 AfricaKenya 36913721 569250 AfricaChina 1321851888 9326410 Asia
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Questions: HTML in VB• Are these correct (assume variables and
fields exist)?
f = f + rs.Fields("Description").value
h = h + rs.Fields("<br />Name").value
a = "<p>" + a "</p>"
html = html + <img src=face.gif />
h = "<table>" + h + "</table>"
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Session Aims & Objectives• Aims
– To add dealing with multiple tables and writing data to your understanding of databases
• Objectives,by end of this week’s sessions, you should be able to:
– identify a suitable primary key for a table– identify duplicated data in a single table– split that table to reduce data redundancy, using a
suitable foreign key– generate SQL statements to (temporarily)
join tables, and use these in your code– create a web page that allows the user to write (store)
data in database
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Data Duplication• Look for repeating data:
Track Title Artist Name Country
Paranoid Black Sabbath UK
Falling in Love Aerosmith US
Pink Aerosmith US
Love in an Elevator Aerosmith US
Smooth Criminal Alien Ant Farm US
Meaning of Life Disturbed US
The Game Disturbed US
Voices Disturbed US
Down with the Sickness Disturbed US
Track
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Problem: Data Duplication• takes up lots of space
• can become inconsistent (misspellings)
• difficult to change (need to change each instance)
• difficult to search (misspellings)
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Solution: Normalisation• Part of database design
• Process of breaking data down (splitting)
• Codd– 7 stages of normalisation
• Mathematical• Difficult to apply stages• Most professionals do it instinctively
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Relations (tables)
Track Title
Paranoid
Falling in Love Aerosmith US
Pink Aerosmith US
Love in an Elevator Aerosmith US
Smooth Criminal Alien Ant Farm US
Meaning of Life Disturbed US
The Game Disturbed US
Voices Disturbed US
Down with the Sickness Disturbed US
Track
Artist Name Country
Black Sabbath UK
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Relations (tables)
Track Title
Paranoid
Falling in Love Aerosmith US
Pink Aerosmith US
Love in an Elevator Aerosmith US
Smooth Criminal Alien Ant Farm US
Meaning of Life Disturbed US
The Game Disturbed US
Voices Disturbed US
Down with the Sickness Disturbed US
Track
Artist ID
1
Artist
Artist Name Country
Black Sabbath UK
ID Artist Name Country
1 Black Sabbath UK
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Relations (tables)
Track Title
Paranoid
Falling in Love
Pink Aerosmith US
Love in an Elevator Aerosmith US
Smooth Criminal Alien Ant Farm US
Meaning of Life Disturbed US
The Game Disturbed US
Voices Disturbed US
Down with the Sickness Disturbed US
Track
Artist ID
1
Artist
ID Artist Name Country
1 Black Sabbath UKAerosmith US
ID Artist Name Country
1 Black Sabbath UK
2 Aerosmith US2
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Relations (tables)
Track Title
Paranoid
Falling in Love
Pink
Love in an Elevator Aerosmith US
Smooth Criminal Alien Ant Farm US
Meaning of Life Disturbed US
The Game Disturbed US
Voices Disturbed US
Down with the Sickness Disturbed US
Track
Artist ID
1
2
2
Artist
ID Artist Name Country
1 Black Sabbath UK
2 Aerosmith US
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Relations (tables)
Track Title
Paranoid
Falling in Love
Pink
Love in an Elevator
Smooth Criminal Alien Ant Farm US
Meaning of Life Disturbed US
The Game Disturbed US
Voices Disturbed US
Down with the Sickness Disturbed US
Track
Artist ID
1
2
2
2
Artist
ID Artist Name Country
1 Black Sabbath UK
2 Aerosmith US
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Relations (tables)
Track Title
Paranoid
Falling in Love
Pink
Love in an Elevator
Smooth Criminal
Meaning of Life Disturbed US
The Game Disturbed US
Voices Disturbed US
Down with the Sickness Disturbed US
Track
Artist ID
1
2
2
2
3
Artist
ID Artist Name Country
1 Black Sabbath UK
2 Aerosmith US
3 Alien Ant Farm US
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Relations (tables)
Track Title
Paranoid
Falling in Love
Pink
Love in an Elevator
Smooth Criminal
Meaning of Life
The Game Disturbed US
Voices Disturbed US
Down with the Sickness Disturbed US
Track
Artist ID
1
2
2
2
3
4
Artist
ID Artist Name Country
1 Black Sabbath UK
2 Aerosmith US
3 Alien Ant Farm US
4 Disturbed US
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Relations (tables)
Track Title
Paranoid
Falling in Love
Pink
Love in an Elevator
Smooth Criminal
Meaning of Life
The Game
Voices Disturbed US
Down with the Sickness Disturbed US
Track
Artist ID
1
2
2
2
3
4
4
Artist
ID Artist Name Country
1 Black Sabbath UK
2 Aerosmith US
3 Alien Ant Farm US
4 Disturbed US
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Relations (tables)
Track Title
Paranoid
Falling in Love
Pink
Love in an Elevator
Smooth Criminal
Meaning of Life
The Game
Voices
Down with the Sickness Disturbed US
Track
Artist ID
1
2
2
2
3
4
4
4
Artist
ID Artist Name Country
1 Black Sabbath UK
2 Aerosmith US
3 Alien Ant Farm US
4 Disturbed US
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Relations (tables)
Track Title Artist ID
Paranoid 1
Falling in Love 2
Pink 2
Love in an Elevator 2
Smooth Criminal 3
Meaning of Life 4
The Game 4
Voices 4
Down with the Sickness 4
Track Artist
ID Artist Name Country
1 Black Sabbath UK
2 Aerosmith US
3 Alien Ant Farm US
4 Disturbed US
PrimaryKey
ForeignKey
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Question: Prescriptions• Identify duplication and separate:
Date Surname Forenames Drug Name
6 Jan 04 Jones Alison Co-codamol
11 Jan 04 Smith Bob Tegretol
18 Jan 04 Hope John Co-codamol
5 Feb 04 Johnson Sally Co-codamol
8 Feb 04 Smith Bob Tegretol
10 Feb 04 Smith Bob Sorbitol
Prescription
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Question: Solution
Date PatientID DrugID
6 Jan 04 1 1
11 Jan 04 2 2
18 Jan 04 3 1
5 Feb 04 4 1
8 Feb 04 2 2
10 Feb 04 2 3
Prescription
PatientID Surname Forenames
1 Jones Alison
2 Smith Bob
3 Hope John
4 Johnson Sally
Patient
DrugID Drug Name
1 Co-codamol
2 Tegretol
3 Sorbitol
Drug
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People Database (with Hobbies)ID Surname Forenames Phone email
1 Dixon Mark 01752 232556 [email protected]
2 Smith John 01752 111111 [email protected]
3 Jones Sally 01752 888888 [email protected]
4 Bloggs Fred 01752 123123 [email protected]
5 Anderson Genny 01752 987987 [email protected]
HobbyID Description PersonID
1 Archery 1
2 Herpetology 1
3 Music 1
4 Football 2
5 Rugby 2
6 Hitting people with swords 1
Hobby
Person
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Entity-relationship diagrams• Each table in db
– stores details of entity• shown as rectangular box
•Relationships between tables
–represent relationships between entities
•shown as line between entities (boxes)
Person Hobby
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Relationship Types• One-to-one
• One-to-many
• Many-to-one
• Many-to-many– (can't be implemented in relational database)
A B
A B
A B
A B
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Question: Which relationship type?
ID Surname Forenames Phone email
1 Dixon Mark 01752 232556 [email protected]
2 Smith John 01752 111111 [email protected]
3 Jones Sally 01752 888888 [email protected]
4 Bloggs Fred 01752 123123 [email protected]
5 Anderson Genny 01752 987987 [email protected]
HobbyID Description PersonID
1 Archery 1
2 Herpetology 1
3 Music 1
4 Football 2
5 Rugby 2
6 Hitting people with swords 1
Hobby
Person
Person
Hobby
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SQL: Joining tables
SELECT * FROM Person, Hobby;
Two tables
Cartesian set(all recordcombinations):
ID Surname Forenames Phone email HobbyID Description PersonID1 Dixon Mark 01752 232556 [email protected] 7 Archery 12 Smith John 01752 111111 [email protected] 7 Archery 13 Jones Sally 01752 888888 [email protected] 7 Archery 14 Bloggs Fred 01752 123123 [email protected] 7 Archery 15 Anderson Genny 01752 987987 [email protected] 7 Archery 11 Dixon Mark 01752 232556 [email protected] 8 Herpetology 12 Smith John 01752 111111 [email protected] 8 Herpetology 13 Jones Sally 01752 888888 [email protected] 8 Herpetology 14 Bloggs Fred 01752 123123 [email protected] 8 Herpetology 15 Anderson Genny 01752 987987 [email protected] 8 Herpetology 11 Dixon Mark 01752 232556 [email protected] 9 Music 12 Smith John 01752 111111 [email protected] 9 Music 13 Jones Sally 01752 888888 [email protected] 9 Music 14 Bloggs Fred 01752 123123 [email protected] 9 Music 15 Anderson Genny 01752 987987 [email protected] 9 Music 11 Dixon Mark 01752 232556 [email protected] 10 Football 22 Smith John 01752 111111 [email protected] 10 Football 23 Jones Sally 01752 888888 [email protected] 10 Football 24 Bloggs Fred 01752 123123 [email protected] 10 Football 25 Anderson Genny 01752 987987 [email protected] 10 Football 21 Dixon Mark 01752 232556 [email protected] 11 Rugby 22 Smith John 01752 111111 [email protected] 11 Rugby 23 Jones Sally 01752 888888 [email protected] 11 Rugby 24 Bloggs Fred 01752 123123 [email protected] 11 Rugby 25 Anderson Genny 01752 987987 [email protected] 11 Rugby 21 Dixon Mark 01752 232556 [email protected] 12 Hitting people with swords 12 Smith John 01752 111111 [email protected] 12 Hitting people with swords 13 Jones Sally 01752 888888 [email protected] 12 Hitting people with swords 14 Bloggs Fred 01752 123123 [email protected] 12 Hitting people with swords 15 Anderson Genny 01752 987987 [email protected] 12 Hitting people with swords 1
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SQL: Joining tables
SELECT *FROM Person, HobbyWHERE Person.ID = Hobby.PersonID;
Two tables
Matching recordsID Surname Forenames Phone email HobbyID Description PersonID
1 Dixon Mark 01752 232556 [email protected] 1 Archery 1
1 Dixon Mark 01752 232556 [email protected] 2 Herpetology 1
1 Dixon Mark 01752 232556 [email protected] 3 Music 1
1 Dixon Mark 01752 232556 [email protected] 6 Hitting people with swords 1
2 Smith John 01752 111111 [email protected] 4 Football 2
2 Smith John 01752 111111 [email protected] 5 Rugby 2
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SQL: Joining tables
ID Surname
1 Dixon
1 Dixon
1 Dixon
1 Dixon
2 Smith
2 Smith
SELECT ID, SurnameFROM Person, HobbyWHERE Person.ID = Hobby.PersonID;
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SQL: More• Loads more:
– group by– aggregate functions: average, count– inner joins– outer joins (left and right)
• Have a look at:– http://www.w3schools.com/sql/sql_join.asp
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Questions: Databases• How many primary keys?• How many foreign keys?
32
PlantPlantID EnglishName ScientificName Price Toxic FileName
1 Foxglove Digitalis purpurea 2.5 TRUE Foxglove.jpg2 Daisy Bellis perennis 0.45 FALSE Daisy.jpg3 Hemlock Conium maculatum 8.79 TRUE Hemlock.jpg4 Marsh Mallow Althaea officinalis 3.25 FALSE MarshMallow.jpg5 Lords-and-Ladies Arum maculatum 2.25 TRUE Lords.jpg6 Wild Carrot Daucus carota 1.25 FALSE WildCarrot.jpg7 Bluebell Hyacinthoides non-scripta 1.8 FALSE Bluebell.jpg8 Common Poppy Papaver rhoeas 1.28 FALSE Poppy.jpg
OrderOrderID CustID PlantID Quantity Date Current
1 1 7 10 14-Mar-06 TRUE2 2 5 2 14-Mar-06 TRUE3 1 3 1 14-Mar-06 FALSE5 2 4 4 14-Mar-06 FALSE
46 1 2 9 09-Jun-06 FALSE
CustomerCustID Surname Forenames email Password
1 Dixon Mark [email protected] a2 Jones Sally [email protected] sally
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Example: Person v1 (Specification)
• User requirement:– Display people's details from database online– need 2 pages:
smithjonesdixon
list of people
jones
person's details
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Example: PeopleList.jsp v1<%@page import="java.sql.*"%><%@page contentType="text/html"%><%Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");Connection cn = DriverManager.getConnection("jdbc:odbc:PeopleDB", "", "");Statement st = cn.createStatement();ResultSet r = st.executeQuery("SELECT * FROM Person;");String html = "";
while(r.next()){
html += r.getString("Surname") + "<br />"; } cn.close();%><!DOCTYPE html><html> <head><title></title></head> <body> <%=html%> </body></html>
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Example: PeopleList.jsp v2<%@page import="java.sql.*"%><%@page contentType="text/html"%><%Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");Connection cn = DriverManager.getConnection("jdbc:odbc:PeopleDB", "", "");Statement st = cn.createStatement();ResultSet r = st.executeQuery("SELECT * FROM Person;");String html = "";String id; while(r.next()){ id = Integer.toString(r.getInt("PersonID")); html += "<a href='Person2.jsp?id=" + id + "'>"; html += r.getString("Surname") + "</a><br />"; } cn.close();%><!DOCTYPE html><html> <head><title></title></head> <body> <%=html%> </body></html>
now links
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Example: Person.jsp v2<%@page import="java.sql.*"%><%@page contentType="text/html" pageEncoding="UTF-8"%><%String id = request.getParameter("id");Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");Connection cn = DriverManager.getConnection("jdbc:odbc:PeopleDB", "", "");Statement st = cn.createStatement();ResultSet r = st.executeQuery("SELECT * FROM Person WHERE PersonID = " + id + ";");String surname = ""; if(r.next()){ surname = r.getString("Surname"); } cn.close();%><!DOCTYPE html><html> <head><title>Person</title></head> <body> Surname: <input name="txtSurname" type="text" value="<%=surname%>" /> </body></html>
reads querystring(from previous page)
displays data forselected record only
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Tutorial Exercise: Person• Task 1: Get the Person (v1) example from
the lecture working.
• Task 2: Modify your code, so that forename is displayed as well as surname (use a table).
• Task 3: Get the Person (v2) example from the lecture working.