1. Introduction to Databases with PostgreSQL
Gabrielle Roth
PDXPUG & FreeGeek
Nov 9, 2010

2. Outline
Intro to Databases (discussion)
PostgreSQL (discussion)
psql (hands-on)
SQL (hands-on)
...break somewhere in here, 7:30...
Practice db + more SQL (hands-on)
Basic Admin + GUI Tools (discussion)
Questions
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 2 / 1

3. Introductions
__ __
/ ~~~/ . o O ( Hi! )
,----( oo )
/ __ __/
/| ( |(
^ /___ / |
|__| |__|-"
Thanks to Hayley J Wakenshaw for the Elephant
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 3 / 1

4. Databases!
A place to keep your data!
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 4 / 1

5. Relational databases
Based on Relational Calculus
Data is stored in ”relations”
”Normalized”
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 5 / 1

6. PostgreSQL
- How do you say that?
- It’s the database *server*
- We think it’s the best.
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 6 / 1

7. Get connected.
chmod 600 /path/to/id_pdxpug
ssh -i /path/to/id_pdxpug pdxpug@207.173.203.228
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 7 / 1

8. Pg command-line interface
- psql
- - -help
- psql -U [username] -d pdxpug
- h
- ?
- other useful commands
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 8 / 1

9. SQL
- Declarative programming language
- ...let’s do ”Hello World”.
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 9 / 1

10. Hello, World.
SELECT ’Hello, World.’;
...oh yeah, and there’s command-completion, too.
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 10 / 1

11. CREATE TABLE
CREATE TABLE animals
(name varchar(32) primary key,
skin varchar(32),
legs int);
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 11 / 1

12. INSERT
INSERT INTO animals
VALUES (’cat’, ’fur’, ’4’);
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 12 / 1

13. multi-valued INSERT
insert into animals
values
(’dog’, ’fur’, ’4’),
(’bird’, ’feathers’, ’2’),
(’snake’, ’scales’, ’0’);
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 13 / 1

14. SELECT
SELECT * FROM animals;
SELECT name, legs FROM animals;
SELECT * FROM animals
ORDER BY name;
SELECT count(*) FROM animals;
SELECT SUM(legs) FROM animals;
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 14 / 1

15. UPDATE
UPDATE animals
SET name = ’kitty’ WHERE name = ’cat’;
SELECT * FROM animals;
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 15 / 1

16. Transactions
BEGIN;
...your stuff...
...check your stuff with a SELECT...
ROLLBACK or COMMIT as desired
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 16 / 1

17. DELETE
BEGIN;
DELETE FROM animals WHERE legs=2;
SELECT * FROM animals;
[ROLLBACK or COMMIT]
SELECT * FROM animals;
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 17 / 1

18. Exercises
- add an animal of your choice
- update its name
- delete all animals with four legs
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 18 / 1

19. MOAR TABLEZ
www.postgresqlguide.com/postgresql-sample-database.aspx
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 19 / 1

20. ERDs
- Entity-Relationship Diagrams
- Graphical representation of the relations
- ...and how they’re connected (JOINed)
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 20 / 1

21. The time has come, the walrus said, to talk of many things.
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 21 / 1

22. Load ’er up!
i /home/pdxpug/create_tables.sql
i /home/pdxpug/populate_tables.sql
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 22 / 1

23. Working with the sample db
- d
- what are these seq relations?
- d item
- s
- e
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 23 / 1

24. DISTINCT
SELECT fname, lname FROM customer
SELECT count(lname) FROM customer;
SELECT DISTINCT lname FROM customer;
SELECT count(DISTINCT(lname)) FROM customer;
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 24 / 1

25. - PRIMARY vs FOREIGN keys
- Natural vs Surrogate keys
- JOINs
- pset null ’[null]’
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 25 / 1

26. JOINs
SELECT * FROM item;
SELECT * FROM stock;
SELECT i.description, i.cost_price, i.sell_price, s.quantity
FROM item i
JOIN stock s ON i.item_id = s.item_id;
SELECT i.description, i.cost_price, i.sell_price, s.quantity
FROM item i
LEFT JOIN stock s ON i.item_id = s.item_id;
SELECT i.description, i.cost_price, i.sell_price, s.quantity
FROM item i
RIGHT JOIN stock s ON i.item_id = s.item_id;Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 26 / 1

27. ...and the dreaded Cartesian JOIN
SELECT * FROM item;
SELECT * FROM stock;
SELECT i.description, i.cost_price, i.sell_price, s.quantity
FROM item i, stock s;
SELECT i.description, i.cost_price, i.sell_price, s.quantity
FROM item i
CROSS JOIN stock s;
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 27 / 1

28. VIEWs and TEMP TABLEs
CREATE VIEW my_view AS SELECT field FROM table;
vs.
CREATE TEMP TABLE my_temp_table AS SELECT field FROM table;
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 28 / 1

29. VIEWs and TEMP TABLEs
CREATE VIEW view_in_stock AS
SELECT i.item_id, i.description, s.quantity
FROM item i
LEFT JOIN stock s ON i.item_id=s.item_id;
SELECT * FROM view_in_stock;
try:
pset null ’0’
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 29 / 1

30. subSELECTs
SELECT date_placed FROM orderinfo
WHERE customer_id IN
(SELECT customer_id FROM customer
WHERE lname = ’Matthew’);
SELECT date_placed FROM orderinfo
WHERE customer_id IN
(SELECT customer_id FROM customer
WHERE (fname, lname) = (’Alex’,’Matthew’));
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 30 / 1

31. Exercises
1 How many items are currently in stock?
2 In which towns do we have customers?
3 Experiment with RIGHT JOIN with the original sample queries.
4 What are the barcodes for each item?
5 What is the name + total ”our cost” value of each item currently in stock?
6 What is the name + total ”selling cost” value of each item currently in stock?
7 What are the total ”our cost” and ”sell cost” values of all items in stock?
8 How much was shipping on each order?
9 What items were ordered by people with the last name ”Stones”?
10 How much was the total shipping per person?
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 31 / 1

32. Basic Admin
- initdb
- PGDATA
- postgresql.conf
- pg hba.conf
- stop/start/restart/reload
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 32 / 1

33. Basic Admin
- SELECT version();
- CREATE ROLE
- backups and upgrades
- pg dump, pg dumpall, pg upgrade
- logs
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 33 / 1

34. GUI Tools
- pHpPgAdmin
- pgAdminIII
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 34 / 1

35. Extras
- Natural keys vs Surrogate keys
- indexes
GRANT USAGE ON SCHEMA [schema] TO [otheruser];
GRANT SELECT ON [table] TO [otheruser];
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 35 / 1

36. Book giveaway!
SELECT (random() * 100);
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 36 / 1

37. Where to get help
- www.postgresql.org/community/lists/
- #postgresql
- PDXPUG
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 37 / 1

38. Reading List
www.postgresql.org/docs
Manga Guide to Databases Takahashi, Mana
Database Design for Mere Mortals Hernandez, Michael J
SQL for Smarties Celko, Joe
Introduction to Database Systems Date, CJ
Relational Model for Database Management Codd, EF
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 38 / 1

39. __ __
/ ~~~/ . o O ( Thank you! )
,----( oo )
/ __ __/
/| ( |(
^ /___ / |
|__| |__|-"
Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 39 / 1