SQL*Plus query: table joins with aggregation - sql

Question

CREATE TABLE users
()
CREATE TABLE avatars
()
CREATE TABLE weapons
()
I need two queries for these tables that I created and I am having trouble doing it, any help would be greatly appreciated.
For all Avatars produce a list showing the avatar name, the total number of weapons it currently holds and the total cost of all weapons currently held. I want no more extra information shown apart from these three main pieces, so I need to get information from table 2 and 3.
For any given User email (i.e. entered at runtime) list the owned Avatar names in reverse order of date of birth and the weapons (including weapon name, range and cost) held by that Avatar.
Any help would be greatly appreciated. I am using SQL*Plus. The tables are not very efficient so any improvements would be welcomed but mainly I need help with these queries.

Answer 1

select
max(a.name),
count(1),
sum(w.cost)
from
avatars a
inner join weapons w on w.weapon_id=a.no_wp_id
group by
a.no_wp_id
;
select
a.name,
w.weapon_name,
w.range,
w.cost
from
users u
inner join avatars a on a.user_id=u.id
inner join weapons w on w.weapon_id=a.no_wp_id
where
u.email='given#email.com'
order by
a.dateOfBirth desc
;
If your queries depend on email being unique, you should have a unique key on it.
Your weapons table does not appear to have a range column on it, but you implied it does in your requirement for query #2. I've included w.range anyway.
In avatars, no_wp_id should probably be named something like avatar_id or just id, and in weapons, weapon_id should be named avatar_id.
You should go through an SQL tutorial. Here's one: http://www.tutorialspoint.com/sql/sql-overview.htm.