RELATIONAL DATABASES SCRG Lab Group Demo, 23 Jan 2012

Outline • Why use a relational database • Best practices for database design • Working with a relational database (MySQL and

phpMyAdmin)

Outline • Why use a relational database • Best practices for database design • Working with a relational database (MySQL and

phpMyAdmin)

A systematic framework for storing and managing data

One size does not fit all

Outline • Why use a relational database • Best practices for database design • Working with a relational database (MySQL and

phpMyAdmin)

Example Data • Talkers

• Sentences • Acoustic analysis on sentences spoken by talkers

“Flat Database” design

“Column Heavy” design

Flat vs. Relational

Flat vs. Relational

Outline • Why use a relational database • Best practices for database design • Working with a relational database (MySQL and

phpMyAdmin)

Basic query • SELECT [columns] FROM [table] WHERE [filters]

• SELECT * FROM `talker` WHERE 1 •  (show all talkers)

• SELECT * FROM `talker` WHERE `age`>=20 •  (get all talkers who are 25 or older)

• SELECT `talkerCode` FROM `talker` WHERE `age`>=20 •  (same as above but only retrieves the talkerCode column)

Combining tables • SELECT [columns] FROM [table1],[table2] WHERE [joins]

AND [filters]

• SELECT * FROM `talker`, `sentenceProduction` WHERE `sentenceProduction`.`talker_id` = `talker`.`talker_id` •  Combines the talkers and sentenceProduction table

• SELECT * FROM `sentence`, `sentenceProduction` WHERE `sentenceProduction`.`sentence_id` = `sentence`.`sentence_id` •  (Combine sentence and sentenceProduction table)

Combining tables SELECT * FROM `talker`, `sentenceProduction` WHERE `sentenceProduction`.`talker_id` = `talker`.`talker_id` AND `talker`.`age` >=20

•  Combines the talkers and sentenceProduction table and only get talkers who are 25 or older

Combining tables SELECT * FROM `talker`, `sentence`, `sentenceProduction` WHERE `sentenceProduction`.`talker_id` = `talker`.`talker_id` AND `sentenceProduction`.`sentence_id`= `sentence`.`sentence_id`

•  Combines the talkers, sentence and sentenceProduction table

Combining tables SELECT `talker`.`talkerCode`, `talker`.`age` FROM `talker`, `sentence`, `sentenceProduction` WHERE `sentenceProduction`.`talker_id` = `talker`.`talker_id` AND `sentenceProduction`.`sentence_id`= `sentence`.`sentence_id`

•  Combines the talkers, sentence and sentenceProduction table and only retrieves the talkerCode and age columns from the talker table

Complex example SELECT `talker`.`talkerCode` , AVG( `sentenceProduction`.`totalDuration` ) AS `avg` , COUNT( * ) AS `number of sentences` FROM `talker` , `sentence` , `sentenceProduction` WHERE `sentenceProduction`.`talker_id` = `talker`.`talker_id` AND `sentenceProduction`.`sentence_id` = `sentence`.`sentence_id` GROUP BY `talker`.`talker_id`

Extra stuff • MySQL + php allows for more complex queries when

necessary •  To try this on your own computer, download and install

XAMPP (http://www.apachefriends.org/en/xampp.html)