TheCrazyMax

--[[
 $Id$

 Copyright © 2007-2018 the VideoLAN team

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2 of the License, or
 (at your option) any later version.

bradtraversy

MongoDB Cheat Sheet

Show All Databases

show dbs

Show Current Database

bradtraversy

[
	{
		"abbr": "AL",
		"name": "Alabama",
		"capital": "Montgomery",
		"lat": "32.361538",
		"long": "-86.279118"
	},
	{
		"abbr": "AK",

ololobus

CREATE TABLE large_test (num1 bigint, num2 double precision, num3 double precision);

INSERT INTO large_test (num1, num2, num3)
  SELECT round(random()*10), random(), random()*142
  FROM generate_series(1, 20000000) s(i);

EXPLAIN (analyse, buffers) 
SELECT num1, avg(num3) as num3_avg, sum(num2) as num2_sum 
FROM large_test
GROUP BY num1;

Kartones

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

• -E: will describe the underlaying queries of the \ commands (cool for learning!)
• -l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

hofmannsven

MySQL

Getting started

• http://www.sqlteaching.com/
• https://www.codecademy.com/learn/learn-sql
• https://www.codecademy.com/catalog/language/sql

Related tutorials

• MySQL-CLI
• Analyzing Business Metrics