Introduction to PostgreSQL

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Introduction to PostgreSQL

  1. 1. Introduction to Databases with PostgreSQL Gabrielle Roth PDXPUG & FreeGeek Nov 9, 2010
  2. 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. 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. 4. Databases! A place to keep your data! Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 4 / 1
  5. 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. 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. 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. 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. 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. 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. 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. 12. INSERT INSERT INTO animals VALUES (’cat’, ’fur’, ’4’); Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 12 / 1
  13. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 34. GUI Tools - pHpPgAdmin - pgAdminIII Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 34 / 1
  35. 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. 36. Book giveaway! SELECT (random() * 100); Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 36 / 1
  37. 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. 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. 39. __ __ / ~~~/ . o O ( Thank you! ) ,----( oo ) / __ __/ /| ( |( ^ /___ / | |__| |__|-" Gabrielle Roth (PDXPUG & FreeGeek) Introduction to Databases with PostgreSQL Nov 9, 2010 39 / 1

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