The document outlines an introduction to databases presentation using PostgreSQL. It includes an introduction to databases concepts, an overview of PostgreSQL, demonstrations of SQL commands like CREATE TABLE, INSERT, SELECT and JOIN in psql, and discussions of database administration and GUI tools. Exercises are provided for attendees to practice the concepts covered.

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
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3. Introductions
__ __
/ ~~~/ . o O ( Hi! )
,----( oo )
/ __ __/
/| ( |(
^ /___ / |
|__| |__|-"
Thanks to Hayley J Wakenshaw for the Elephant
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4. Databases!
A place to keep your data!
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5. Relational databases
Based on Relational Calculus
Data is stored in ”relations”
”Normalized”
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6. PostgreSQL
- How do you say that?
- It’s the database *server*
- We think it’s the best.
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7. Get connected.
chmod 600 /path/to/id_pdxpug
ssh -i /path/to/id_pdxpug pdxpug@207.173.203.228
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8. Pg command-line interface
- psql
- - -help
- psql -U [username] -d pdxpug
- h
- ?
- other useful commands
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9. SQL
- Declarative programming language
- ...let’s do ”Hello World”.
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10. Hello, World.
SELECT ’Hello, World.’;
...oh yeah, and there’s command-completion, too.
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11. CREATE TABLE
CREATE TABLE animals
(name varchar(32) primary key,
skin varchar(32),
legs int);
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12. INSERT
INSERT INTO animals
VALUES (’cat’, ’fur’, ’4’);
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13. multi-valued INSERT
insert into animals
values
(’dog’, ’fur’, ’4’),
(’bird’, ’feathers’, ’2’),
(’snake’, ’scales’, ’0’);
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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;
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15. UPDATE
UPDATE animals
SET name = ’kitty’ WHERE name = ’cat’;
SELECT * FROM animals;
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16. Transactions
BEGIN;
...your stuff...
...check your stuff with a SELECT...
ROLLBACK or COMMIT as desired
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17. DELETE
BEGIN;
DELETE FROM animals WHERE legs=2;
SELECT * FROM animals;
[ROLLBACK or COMMIT]
SELECT * FROM animals;
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18. Exercises
- add an animal of your choice
- update its name
- delete all animals with four legs
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19. MOAR TABLEZ
www.postgresqlguide.com/postgresql-sample-database.aspx
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20. ERDs
- Entity-Relationship Diagrams
- Graphical representation of the relations
- ...and how they’re connected (JOINed)
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21. The time has come, the walrus said, to talk of many things.
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22. Load ’er up!
i /home/pdxpug/create_tables.sql
i /home/pdxpug/populate_tables.sql
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23. Working with the sample db
- d
- what are these seq relations?
- d item
- s
- e
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24. DISTINCT
SELECT fname, lname FROM customer
SELECT count(lname) FROM customer;
SELECT DISTINCT lname FROM customer;
SELECT count(DISTINCT(lname)) FROM customer;
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25. - PRIMARY vs FOREIGN keys
- Natural vs Surrogate keys
- JOINs
- pset null ’[null]’
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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;
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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;
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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’
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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’));
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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?
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32. Basic Admin
- initdb
- PGDATA
- postgresql.conf
- pg hba.conf
- stop/start/restart/reload
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33. Basic Admin
- SELECT version();
- CREATE ROLE
- backups and upgrades
- pg dump, pg dumpall, pg upgrade
- logs
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34. GUI Tools
- pHpPgAdmin
- pgAdminIII
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35. Extras
- Natural keys vs Surrogate keys
- indexes
GRANT USAGE ON SCHEMA [schema] TO [otheruser];
GRANT SELECT ON [table] TO [otheruser];
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36. Book giveaway!
SELECT (random() * 100);
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37. Where to get help
- www.postgresql.org/community/lists/
- #postgresql
- PDXPUG
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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
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39. __ __
/ ~~~/ . o O ( Thank you! )
,----( oo )
/ __ __/
/| ( |(
^ /___ / |
|__| |__|-"
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