Best solution for SQL without looping - sql

Question

I'm relatively new to SQL, and am trying to find the best way to attack this problem.
I am trying to take data from 2 tables and start merging them together to perform analysis on it, but I don't know the best way to go about this without looping or many nested subqueries.
What I've done so far:
I have 2 tables. Table1 has user information and Table2 has information on orders(prices and dates, as well as user)
What I need to do:
I want to have a single row for each user that has a summary of information about all of their orders. I'm looking to find the sum of prices of all orders by each user, the max price paid by that user, and the number of orders. I'm not sure how to best manipulate my data in SQL.
Currently, my code looks as follows:
Select alias1.*, Table2.order_id, Table2.price, Table2.order_date
From (Select * from Table1 where country='United States') as alias1
LEFT JOIN Table2
on alias1.user_id = Table2.user_id
This filters out the datatypes by country, and then joins it with users, creating a record of each order including the user information. I don't know if this is a helpful step, but this is part of my first attempt playing around with the data. I was thinking of looping over this, but I know that is against the spirit of SQL
Edit: Here is an example of what I have and what I want:
Table 1(user info):
user_id user_country
1 United States
2 United Kingdom
(etc)
Table 2(order info):
order_id price user_id
100 5.00 1
101 3.50 2
102 2.50 1
103 1.00 1
104 8.00 2
What I would like output:
user_id user_country total_price max_price number_of_orders
1 United States 8.50 5.00 3
2 United Kingdom 11.50 8.00 2

Answer 1

Here's one way to do this:
SELECT alias1.user_id,
MAX(alias1.user_name) As user_name,
SUM(Table2.price) As UsersTotalPrice,
MAX(Table2.price) As UsersHighestPrice
FROM Table1 As alias1
LEFT JOIN Table2 ON alias1.user_id = Table2.user_id
WHERE country = 'United States'
GROUP BY user_id
If you can give us the actual table definitions, then we can show you some actual working queries.

Answer 2

Something like this? Agregate the rows in table2 and then join to table 1 for the detail info you want?
SELECT Table1.*,agg.thesum FROM
(SELECT UserID, SUM(aggregatedata) as thesum FROM Table2 GROUP BY UserID) agg
INNER JOIN Table1 on table1.userid = agg.userid

Answer 3

This should work
select table1.*, t2.total_price, t2.max_price, t2.order_count
from table1
join (selectt user_id, sum(table2.price) as total_price, max(table2.price) as max_price, count(order_id) as order_count from table2 as t2 group by t2.user_id)
on table1.user_id = t2.user_id
where t1.country = 'untied_states'

Answer 4

EDIT: (removed:"dont use explicit join" this was wrong, I meant:)
Try to use the following Sytax, for better understanding what goes on:
1st step:
select
user.user_id, -- < you must tell the DB userid of which column
user_country,
price,
price
from -- now just the two tables:
Table1 as user, --table1 is a bad name, we use 'user'
Table2 as order
where user.user_id = order.user_id
so you will get somthing like:
user_id user_country price price
1 alabama 5 5
2 nebrasca 1 1
2 alabama 7 7
1 alabama 7 7
2 alabama 3 7
and so on ..
the next step is to add an other where usercountry='alabama' so 'nebrasca' is off
user_id user_country price price
1 alabama 5 5
2 alabama 7 7
1 alabama 7 7
2 alabama 3 7
now you are ready for "aggregate": just select the MAX and SUM of price, but you have to tell the SQL engine what columes are 'fixed' = group by
select
user.user_id, user_country, MAX(price), SUM(price)
from
Table1 as user,
Table2 as order
where user.user_id = order.user_id
and user_country='alabama'
group by user_id, user_country