install: sudo apt-get install postgresql
	sudo apt-get install pgadmin3

start service: sudo service postgresql start

password: sudo -u postgres psql 
	pgdb


login: psql -h localhost -U postgres database

types:
	numeric(a,b)

date/time functions:
	age(timestamp, timestamp) -> interval
	age(timestamp)
	extract(field from interval) -> double precision
	today: current_date

check null: where col is null

like pattern
	% is like *

string concat: ||
	'preformatted % string', val
	length()

conditional expr: case where e1 then r1 ... else rn end

average: avg(*)

operations:
	create database:
		from command line createdb, dropdb
	show databases: select datname from pg_database;
	execute: execute script
		sudo -u postgres psql -f script.sql databaseName
		\i filename.sql
	show tables: select table_name from information_schema.tables where table_type = 'BASE TABLE' and table_schema not in ('pg_catalog', 'information_schema');

PL/pgSQL functions:
	structure:
		drop function fname(type,...)
		create [or replace] function fname(arg type, ...)
		returns retype as $$
		[ declare
			< declarations > ]
		begin
			< statements >
		end;
		$$ language plpgsql;
	retype: integer, table...
	declaration:
		quantity integer := 30;
		tbl_row tbl%rowtype;
	statement:
		quantity := 4;
		if quantity < 5 then
			quantity := 5;
		end if;
		while quantity < 10 loop
			quantity := quantity + 1
		end loop;
		for tblrow in select * from tb loop
			use tblrow.colname
		end loop;
		select count (*) into varname from ...
		return varname (can return multiple times)
		raise warning string
	usage:
		select fname(val);
		select * from fname(vals);

triggers:
	structure:
		create trigger name
		before/after insert/delete or update
		on table
		for each row
		body
	in an insert use new.cols