lk/data/sql/sql.md

MySQL, Aurora and the Maria Database work similarly, and mostly with the same commands.

MySQL requires 160 Megs of disk space.

The ontological layers go:

Database > table > record > field

The record is a line containing multiple fields. The table contains multiple records.

Database: RPGs

Table: D&D

Columns:

id	name	year	edition	stars
1	Dungeons & Dragons	1975	1	1
2	Dungeons & Dragons	1980	2	1
3	Advanced Dungeons & Dragons	1985	1	1

Getting started

sudo apt-get install mysql-server

You'll be asked for a password.

Log in with:

mysql -u root -p

The -u requests a user, while -p tells it to prompt for a password.

List all databases:

show databases;

Make a new database;

create database creatures;

Start work on the new database:

use creatures;

create table stats (Strength VARCHAR(2), Speed VARCHAR(2), Dexterity(2));

This creatures a row called 'stats' within the 'creature'table' with a number of variables, all of type VARCHAR (a variable length character string).

Now you can insert data (which would normally be provided by a user via php or some-such).

insert into stats (Strength,Speed,Dexterity) values (-1,0,+1)

Now have a look at the info:

select * from stats

The old way to delete info by selection was:

delete * from stats where Charisma='0'

...but now it's:

delete from stats where Charisma='0'

Update a thing:

update stats

set Speed='-1',Charisma='-2'

where Strength=0;

Leaving out the specifier 'where' means you're updating the entire database.

Control order with

SELECT * FROM stats ORDER BY Strength;

Or for descending order, suffix 'DESC'.

select * from stats ORDER by Date DESC;

Resources

Try more at w3schools.