1. Creating Databases for Web applications
SQL. XML. Linked Lists. NoSQL.
Homework: Keep working on projects. Post constructive feedback on other projects.

2. XML Template for a structured form of data, namely tree:
nodes and child nodes
attributes
text content
Note: some call this semi or partially structured
some elements may NOT have all attributes or child nodes
Developers create and agree on structure
Intended for use by different applications
JavaScript, php, other languages have built-in methods.
Human readable
Not particularly compact, nor speedy in terms of processing.
A [long] text field is read in and interpreted.
Generally, a copy of the XML file is generated and sent to be used by an application.

3. XML example <book isbn="978-1-4302-4032-7">
<type value="nonfiction">
<subtype value="computing"/>
<level value="professional"/>
</type>
<title>HTML5 and JavaScript Projects</title>
<publisher>
<pname>Apress</pname>
<website>
</publisher>
</book>
I made all this up. There probably exist more than one XML schema for books.

4. More…
Many technologies/standards around XML, including ways to specify definitions, do queries, etc.
Posting opportunity….

5. Question?
What are uses for XML?

6. Example Define XML for corporate 'family' tree
a company can have subsidiaries
decide on the information
in attributes
in element contents
in child elements

7. Linked lists Example [You may have worked on this in Data Structures.]
Multiple ways. This is one way.
Information is parent and children
Data contained in one big array of arrays
Each component array is
[name, index first child, index next sibling]
Use -1 to indicate no child or no next sibling.

8. My family ignore in-laws…. one parent for each child 0 Esther 1 -1
Anne
Jeanine
David
Daniel
Tom
Aviva
Annika
Note: other orders would be valid

9. Your family Leave out a parent and in-laws OR come up with alternative
One possibility is to include all half/step siblings or
Another possibility is to add fields for siblings from the father versus siblings from the mother
OR ???

10. Contrast with Relational Database
Tables, records, fields with some fields indicating relationships, i.e., pointing to records using primary key as the foreign key
Commercial products and open source products (MySQL) store data efficiently, perform operations quickly, provide many functions.
DBMS also holds the data itself. One copy of information is maintained and accessed by the different applications.

11. Relational Database family
Two tables
People and relationships
Relationships have fields for two people PLUS label for relationship.
Allow multiple relationships.

12. My family: people table
Esther
Anne
Jeanine
Daniel
Aviva
David
Tommy
Debbie
Annika
Liam
Grant
Allison …

13. My family: relationships
r_id id for Esther id for Jeanine mother
r_id id for Esther id for Anne mother ….

14. Your family
Write out at least 5 family members and at least 5 relationships…

15. NoSQL Alternatives to SQL MongoDB

16. Key-value pairs The data is a set of key-value pairs
The input values passed from a form to a php file
Associative array
Options to set up map using Google Maps API
They may or may not be unique, that is, a specific key may have more than one value

17. Parallel structures Recall simple states capitals quiz
May have more than 2 arrays of corresponding data

18. So….
You may come into a situation with this question already resolved. Data exists in some form already OR your teacher says use this…
OR you need to decide
Parallel structures? Key-value? Does the tree structure suit the data? Or would tables be better?
Is the place of the data important or sending copies around okay, even appropriate
read-only most of the time? ?

19. XML in a database A field in the table is suitable for XML data
Can use a long text datatype called BLOB
MySql stores and returns the text.

20. MySQL XML functions
These use a special language called XPATH to indicate how to interpret the XML.
EXTRACTVALUE
SELECT EXTRACTVALUE(fieldname,XPATH expression) FROM tablename
SELECT as fname FROM my_table WHERE row_id=10
The resultset reflects the results!
UPDATEXML
UPDATEXML(fieldname,XPATH expression indicating replacement in places where there are matches, replacement text)
UPDATE my_table SET xml_text = UpdateXML(xml_text,'//age','<age>30</age>') WHERE row_id=10
These can be used in direct MySQL coding including coding to be saved as STORED PROCEDURE.

21. SQL injection What if dtext was 50 then
Technique by which malicious user enters input that can change result of SQL statement.
Say a piece of text, dtext, is taken to be the id field for all records to be deleted from the database. The assumed usage is that it is just one id.
What if dtext was 50 then
DROP FROM customers WHERE id=dtext would drop record with id 50
What if dtext was 0 or true then DROP FROM customers where id=50 or TRUE would drop everything
There are techniques to prevent these (such as input=number) but they can be more complicated.

22. Extra credit opportunities
NOT just a link. Read and report on what you learn.
expressions involving DATE, TIMESTAMP, etc.
stored procedures in general
MySql standalone coding
XML in MySQL
NoSQL or MongoDB
Hadoop
SQL injection
Ajax
Cloud computing
???

23. Homework Keep working on final projects.
Post on topics mentioned (SQL injection, NoSQL, etc.)
Post constructive feedback on other projects to their posting on Proposals forum.