1. Review Databases and Objects
CCT395, Week 9
Review
Databases and Objects
Yuri Takhteyev
University of Toronto
November 3, 2010
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2. - Proposals & projects - Schedule & readings - The exam - Next class
Announcements
- Proposals & projects
- Schedule & readings
- The exam
- Next class

3. João's Coffee

4. And there is probably more!
The Entities
Coffee shop
Representative
Shipper
Estate
Coffee
Batch
Warehouse
Exchange Rate
Invoice
And there is probably more!

5. Divide and Conquer Grouping João's concerns:
- Getting customers the right coffee
- Tracking deliveries
- Tracking money

6. Divide and Conquer Getting the customers the right coffee
- Ordering the right coffee
- Delivering the coffee to the right
customers

7. The Coffee Estate name, description Region Variety Request
quantity, what kind, who requested
Shipment
quantity, what kind of coffee

8. let's leave for later whose request it is Region Estate Variety
name
description
Estate
name
description
Variety
name
description
Shipment
quantity
date ordered
Request
quantity
date
let's leave for later
whose request it is

9. ? Region Estate Variety Request Shipment ------------- name
description
Estate
name
description
Variety
name
description ?
Request
quantity
date
Shipment
quantity
date ordered

10. Region Estate Variety Harvest Request Shipment ------------- name
description
Estate
name
description
Variety
name
description
Harvest
year
notes
Request
quantity
date
Shipment
quantity
date ordered

11. Region Estate Variety Harvest Request Shipment ------------- name*
description
Estate
name*
description
Variety
name*
description
Harvest
year
notes
Request
quantity
date
Shipment
quantity
date ordered

12. Region Estate Variety Harvest Request Shipment year notes
name
description
Estate
name
description
Variety
name
description
Harvest
year
notes
Request
quantity
date
Shipment
quantity
date ordered

13. For those two we could consider using foreign keys as PKs
Region
region_id*
name
description
Estate
estate_id*
name
description
For those two we could consider using foreign keys as PKs
Variety
variety_id*
name
description
Harvest
harvest_id*
year
notes
Request
quantity
date
Shipment
shipment_id*
quantity
date ordered

14. No longer a pure ER diagram!
Region
region_id*
name
description
Estate
estate_id*
region_id
name
description
No longer a pure ER diagram!
Variety
variety_id*
name
description
Harvest
harvest_id*
variety_id
estate_id
year
notes
Request
harvest_id
shipment_id
quantity
date
Shipment
shipment_id*
quantity
date ordered

15. A Relation harvest (harvest_id*, variety_id, estate_id, year, notes)
harvest (harvest_id*, year, notes)

16. harvest ( harvest_id*, variety_id, estate_id, year, notes )
A Relation
harvest (
harvest_id*,
variety_id,
estate_id,
year,
notes )

17. SQL create table harvest ( harvest_id int, variety_id int,
foreign key (variety_id)
references variety(variety_id),
estate_id int,
foreign key (estate_id)
references estate(estate_id),
year year,
notes varchar(200),
primary key (harvest_id), );

18. to be continued

19. Projects PHP Resources http://www.w3schools.com/php/default.asp
the Menagerie Web example
Get the database done first
Do basic features before the advanced
The 6th bullet point of section 2.2 is now optional
Advanced features
just do two
Don't hesitate to ask questions!

20. Advanced Features Login Store the password in the database
Ideally, use md5() to store a “hash” of a function
Have the user enter a username and password
Check what the user's password should be
Compare this with what they entered
If using md5(), compare the hashes.
If you can, use PHP sessions to remember the user. Otherwise, just have them enter the password every time.

21. Advanced Features Enabling Modifications
Do an INSERT or UPDATE based on the form data
Backup
mysqldump is the simplest option
XML Output
See examples from last week's class
Make sure your XML validates:
r.asp

22. Advanced Features Transactions
Chapter 13 in SQL – we are not covering this
Stored Procedures
SQL chapter 14. Again, we are not covering this
Publicly Available Data
I.e., using “real” data

23. Objects

24. Models Relational: - good for retrieval and updates Document:
- good for exchange of data
Objects:
- good for active manipulation
- good for changing software

25. “Need to know” basis (fewer assumptions → easier to make changes)
Encapsulation
“Need to know” basis
(fewer assumptions →
easier to make changes)

26. Region Estate Variety Harvest Request Shipment harvest_id* year notes
region_id*
name
description
Estate
estate_id*
region_id
name
description
Variety
variety_id*
name
description
Harvest
harvest_id*
variety_id
estate_id
year
notes
Request
harvest_id
shipment_id
quantity
date
Shipment
shipment_id*
quantity
date ordered

27. Messages aka “methods” Harvest get_estate() set_estate() get_variety()
get_estate()
set_estate()
get_variety()
set_variety()
...

28. The Implementation Harvest Estate estate variety year notes get_name()
estate
variety
year
notes
Estate
get_name()
set_name()
get_descript()
set_descript()
...

29. Object-Oriented Programming (OOP)
$harvest = $order->getHarvest();
$estate = $harvest->getEstate();
$estate->setName(“Boa Vista”);
Harvest
get_estate()
set_estate()
get_variety()
set_variety()
...
Estate
get_name()
set_name()
get_descript()
set_descript()
...
Object-Oriented Programming (OOP)

30. PHP with MySQL Don't forge the PHP Tutorial:
$query = "select name, species from pet where owner='"
. $owner . "'";
$result = mysql_query($query);
while ($row = mysql_fetch_array($result)) {
echo "<tr>";
echo "<td>" . $row['name'] . "</td>";
echo "<td>" . $row['species'] . "</td>";
echo "</tr>"; }
Don't forge the PHP Tutorial:

31. Updating the Data $query = "update pet set species='"
. $species . "' where name='";
. $name . "'";
$result = mysql_query($query);
echo "ok";

32. Select and Update
$query = "select name, species from pet where owner='"
. $owner . "'";
$result = mysql_query($query);
while ($row = mysql_fetch_array($result)) {
$name = $row['name'];
echo "Let's change the species of ";
echo $name . " from " . $row['species'];
echo " to " . $new_species;
$update_query = "update pet set species='"
. $new_species . "' where name='";
. $name . "'";
$update_result = mysql_query($query); }

33. What We Want $pets = $menagerie->get_pets_by_owner($owner);
while ($pet = $pets->next()) {
echo "Let's change the species of ";
echo $pet->get_name() . " from " . $pet->get_species();
echo " to " . $new_species;
$pet->set_name($new_species);
$menagerie->save(); }

34. Or Even 1. Easier / more intuitive 2. Encapsulation simplifies reuse
$pets = $menagerie->get_pets_by_owner($owner);
while ($pet = $pets->next()) {
echo "Let's change the species of ";
echo $pet->name . " from " . $pet->species;
echo " to " . $new_species;
$pet->name = $new_species;
$menagerie->save(); }
1. Easier / more intuitive
2. Encapsulation simplifies reuse
Too good to be true?

35. Object-Relational Mapping
Option 1:
Map objects to relations
(code → database)
Option 2:
Map relations to objects
(database → code)

36. Option 2 Manual: We setup a mapping pet.name → getName($name)
setName($name)
Automatic:
The software figures it out
(“introspection”)

37. Examples Rails / ActiveRecord (Ruby) Django (Python) Hibernate (Java)
Doctrine (PHP)

38. Questions?