CS 185C/286: The History of Computing October 31 Class Meeting Department of Computer Science San Jose State University Fall 2011 Instructor: Ron Mak mak.

CS 185C/286: The History of Computing October 31 Class Meeting

Department of Computer ScienceSan Jose State University

Fall 2011Instructor: Ron Mak

www.cs.sjsu.edu/~mak

Department of Computer ScienceFall 2011: October 31

CS 185C/286: History of Computing© R. Mak

2

Don Chamberlin

History of Computing Speaker Wednesday, Nov. 2, 6:00-7:00 PMAuditorium ENGR 189 Reception before the talk in

ENGR 294 at 5:00 PM “Fifty Years of Data:

How Advances in Database Management Have Helped to Shape Our World” Co-inventor of the SQL and

XQuery database languages



3

What is a Database?

A collection of information that lasts over a long period of time Can be accessed simultaneously by multiple

instances of an application or by instances of many applications

Managed by a database management system (DBMS)_



4

Database Management System (DBMS)

Users can create new databases Specify the structure of the data (schema)

Users can query (ask questions about) the data Users can modify the data Store large amounts (terabytes) of data Store data for a long time (many years) Ensure reliability

Recover from errors and failures Ensure data integrity

Maintain proper relationships among data



5

DBMS, cont’d

Control access to data by multiple users and applications

Ensure data operations are completed (atomicity) roll back partially completed operations

Maintain a data model, which determines: structure of the data operations on the data constraints on the data

Types of data models - hierarchical - relational - object-oriented - object-relational



6

The Relational Data Model

Data element: a value that is stored in the database values are typed a value can be null

Entity: a group of data elements that together are meaningful for a person or an application Each data element is the value of an attribute

of the entity_



7

The Relational Data Model, cont’d

Table: a conceptual two-dimensional structure that contains entities of a particular type. Also called a relation Each row (also called a record) contains the

attribute values of one entity. Each column (also called a field) holds an

attribute value.

Table relation Row entity Rows and columns records and fields



8

Logical Data Model Initial version

Id Name Class_code Subject Room

7003 Rogers, Tom 926 Java programming 101

7008 Thompson, Art 908 Data structures 114

7012 Lane, John 951 Software engineering 210

7012 Lane, John 974 Operating systems 109

7051 Flynn, Mabel 931 Compilers 222

John Lane teachestwo classes.

Each table has a primary key (PK) field whose value in each record uniquely identifies that record.

Id Name Teacher_id_1 Teacher_id_2 Teacher_id_3

1001

Doe, John 7003 7012 7008

1005

Novak, Tim 7012 7008 null

1009

Klein, Leslie null null null

1014

Jane, Mary 7051 null null

1021

Smith, Kim 7003 7012 7051

Student

Teacher

Student id name which teachers

Teacher id name which classes

taught

Class class code subject name class room number

PK

PK



9

Normalization

Relational tables need to be normalized. Improve the stability of the model

More resilient to change

Faster record insertions and updates Improve data quality

There are six normal forms, but we will only consider the first two. Each normal form includes the lower normal forms

Example: A database in second normal form is also in first normal form.



10

First Normal Form (1NF)

Separate multi-valued data elements. Break the name fields into last name and first name fields.

Id Last First Teacher_id_1 Teacher_id_2 Teacher_id_3

1001 Doe John 7003 7012 7008

1005 Novak Tim 7012 7008 null

1009 Klein Leslie null null null

1014 Jane Mary 7051 null null

1021 Smith Kim 7003 7012 7051

Id Last First Class_code Subject Room

7003 Rogers Tom 926 Java programming 101

7008 Thompson Art 908 Data structures 114

7012 Lane John 951 Software engineering 210

7012 Lane John 974 Operating systems 109

7051 Flynn Mabel 931 Compilers 222

Student

Teacher

Id Name Teacher_id_1 Teacher_id_2 Teacher_id_3

1001

Doe, John 7003 7012 7008

1005

Novak, Tim 7012 7008 null

1009

Klein, Leslie null null null

1014

Jane, Mary 7051 null null

1021

Smith, Kim 7003 7012 7051Id Name Class_code Subject Room

7003 Rogers, Tom 926 Java programming 101

7008 Thompson, Art 908 Data structures 114

7012 Lane, John 951 Software engineering 210

7012 Lane, John 974 Operating systems 109

7051 Flynn, Mabel 931 Compilers 222



11

First Normal Form, cont’d Move repeating data elements

to a new table.

Id Last First

1001 Doe John

1005 Novak Tim

1009 Klein Leslie

1014 Jane Mary

1021 Smith Kim

Student_id Teacher_id

1001 7003

1001 7012

1001 7008

1005 7012

1005 7008

1014 7051

1021 7003

1021 7012

1021 7051

Linkingtable







Student

Teacher

Student_Teacher

Id Last First Teacher_id_1 Teacher_id_2 Teacher_id_3

1001 Doe John 7003 7012 7008

1005 Novak Tim 7012 7008 null

1009 Klein Leslie null null null

1014 Jane Mary 7051 null null

1021 Smith Kim 7003 7012 7051



12

Problem!

Suppose Prof. Lane decides he doesn’t want to teach Operating Systems anymore and we delete that row.

What other information do we lose as a result? We lose the fact that the class is taught in Room 109.

The problem arises because the Teacher table really contains two separate sets of data: teacher data and class data







Teacher



13

Second Normal Form

Keep related data together (cohesiveness).

Id Last First

7003 Rogers Tom

7008 Thompson Art

7012 Lane John

7051 Flynn Mabel

Class_code Teacher_id Subject Room

908 7008 Data structures 114

926 7003 Java programming 101

931 7051 Compilers 222

951 7012 Software engineering 210

974 7012 Operating systems 109

Teacher Class

Primary key (PK)

Primary key (PK) Foreign key (FK)



14

Final Database Structure

Id Last First

1001 Doe John

1005 Novak Tim

1009 Klein Leslie

1014 Jane Mary

1021 Smith Kim

Code Teacher_id Subject Room






Student_id Class_code

1001 926

1001 951

1001 908

1005 974

1005 908

1014 931

1021 926

1021 974

1021 931

Id Last First

7003 Rogers Tom

7008 Thompson Art

7012 Lane John

7051 Flynn Mabel

Teacher

Student

Class

Student_Class John Doe takes Java programming, software engineering, and data structures.

The Java Programming class has John Doeand Kim Smith.

Mabel Flynn teaches compilers.



15

SQL

Structured Query Language (SQL) An industry standard But has many proprietary extensions

Language for managing data in a relational database Create and drop (delete) databases Create, alter, and drop tables of a database Retrieve, insert, update, and delete data

in the tables._



16

SQL Query Examples

What is the class code of the Java programming class?







Class

SELECT code FROM class WHERE subject = 'Java programming'

+------+| code |+------+| 926 |+------+

Source tables

Desired fields

Selection criteria

Query

Results



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SQL Query Examples, cont’d

Who is teaching Java programming?

Id Last First

7003 Rogers Tom

7008 Thompson Art

7012 Lane John

7051 Flynn Mabel







ClassTeacher

SELECT first, last FROM teacher, classWHERE id = teacher_id AND subject = 'Java programming'

+-------+--------+| first | last |+-------+--------+| Tom | Rogers |+-------+--------+

Selecting from multiple tablesis called a join.



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What classes does John Lane teach?

SELECT code, subjectFROM teacher, classWHERE last = 'Lane' AND first = 'John'AND id = teacher_id

+------+----------------------+| code | subject |+------+----------------------+| 951 | Software engineering || 974 | Operating systems |+------+----------------------+

Id Last First

7003 Rogers Tom

7008 Thompson Art

7012 Lane John

7051 Flynn Mabel







ClassTeacher



19

SQL Query Examples, cont’d Who is taking Java programming?

Id Last First

1001 Doe John

1005 Novak Tim

1009 Klein Leslie

1014 Jane Mary

1021 Smith Kim








1001 926

1001 951

1001 908

1005 974

1005 908

1014 931

1021 926

1021 974

1021 931

SELECT id, last, firstFROM student, class, student_classWHERE subject = 'Java programming'AND code = class_code AND id = student_id

+------+-------+-------+| id | last | first |+------+-------+-------+| 1001 | Doe | John || 1021 | Smith | Kim |+------+-------+-------+

Class

Student_Class

Student



20

SQL Query Examples, cont’d Who are John Lane’s students and in which subjects?

Id Last First

1001 Doe John

1005 Novak Tim

1009 Klein Leslie

1014 Jane Mary

1021 Smith Kim








1001 926

1001 951

1001 908

1005 974

1005 908

1014 931

1021 926

1021 974

1021 931

Id Last First

7003 Rogers Tom

7008 Thompson Art

7012 Lane John

7051 Flynn Mabel

Teacher StudentClass

Student_Class



21


Id Last First

1001 Doe John

1005 Novak Tim

1009 Klein Leslie

1014 Jane Mary

1021 Smith Kim








1001 926

1001 951

1001 908

1005 974

1005 908

1014 931

1021 926

1021 974

1021 931

SELECT student.first, student.last, subjectFROM student, teacher, class, student_classWHERE teacher.last = 'Lane' AND teacher.first = 'John'AND teacher_id = teacher.idAND code = class_code AND student.id = student_idORDER BY subject, student.last

+-------+-------+----------------------+| first | last | subject |+-------+-------+----------------------+| Tim | Novak | Operating systems || Kim | Smith | Operating systems || John | Doe | Software engineering |+-------+-------+----------------------+

Id Last First

7003 Rogers Tom

7008 Thompson Art

7012 Lane John

7051 Flynn Mabel

Teacher StudentClass

Student_Class

Who are John Lane’s students and in which subjects?



22

XML Data

Data can also be stored as XML

XQuery is designed to query XML data SQL : relational databases XQuery : XML

_



23

XQuery Examples

Query:What titles are in the bookstore?

doc("books.xml")/bookstore/book/title

Results:<title lang="en">Everyday Italian</title><title lang="en">Harry Potter</title><title lang="en">XQuery Kick Start</title><title lang="en">Learning XML</title>

<bookstore>

<book category="COOKING"> <title lang="en">Everyday Italian</title> <author>Giada De Laurentiis</author> <year>2005</year> <price>30.00</price></book>

<book category="CHILDREN"> <title lang="en">Harry Potter</title> <author>J.K. Rowling</author> <year>2005</year> <price>29.99</price></book>

<book category="WEB"> <title lang="en">XQuery Kick Start</title> <author>James McGovern</author> <author>Per Bothner</author> <author>Kurt Cagle</author> <author>James Linn</author> <author>Vaidyanathan Nagarajan</author> <year>2003</year> <price>49.99</price></book>

<book category="WEB"> <title lang="en">Learning XML</title> <author>Erik T. Ray</author> <year>2003</year> <price>39.95</price></book>

</bookstore>



24

XQuery Examples, cont’d<bookstore>

<book category="COOKING"> <title lang="en">Everyday Italian</title> <author>Giada De Laurentiis</author> <year>2005</year> <price>30.00</price></book>

<book category="CHILDREN"> <title lang="en">Harry Potter</title> <author>J.K. Rowling</author> <year>2005</year> <price>29.99</price></book>

<book category="WEB"> <title lang="en">XQuery Kick Start</title> <author>James McGovern</author> <author>Per Bothner</author> <author>Kurt Cagle</author> <author>James Linn</author> <author>Vaidyanathan Nagarajan</author> <year>2003</year> <price>49.99</price></book>

<book category="WEB"> <title lang="en">Learning XML</title> <author>Erik T. Ray</author> <year>2003</year> <price>39.95</price></book>

</bookstore>

Query:Which books cost less than $30?

doc("books.xml")/bookstore/book[price<30]

Results:<book category="CHILDREN"> <title lang="en">Harry Potter</title> <author>J.K. Rowling</author> <year>2005</year> <price>29.99</price></book>

CS 185C/286: The History of Computing October 31 Class Meeting Department of Computer Science San Jose State University Fall 2011 Instructor: Ron Mak mak.

Documents

data slide

data users

data operations

years of data

data integrity

data constraints

data schema users

cs 185c286