Question

I have a table called orders where I store information about orders made by an User.

order_id    |   user_id |   amount
+++++++++++++++++++++++++++++++++++
1           |   1       |   100
2           |   1       |   200
3           |   2       |   200
4           |   3       |   100
5           |   3       |   100
6           |   4       |   500

What I want as final outcome is,
Number of Orders made by an user and total value of those orders.

So in above case output should look like,

user_id     |   count   |   sum
+++++++++++++++++++++++++++++++++++
1           |   2       |   300
2           |   1       |   200
3           |   3       |   600
4           |   1       |   500

Answer 1

What you need here is, just a GROUP BY with COUNT and SUM like so:

SELECT
  user_id,
  COUNT(User_id) Count,
  SUM(amount) Sum
FROM Orders
GROUP BY user_id;

SQL Fiddle Demo

This will give you:

| USER_ID | COUNT | SUM |
-------------------------
|       1 |     2 | 300 |
|       2 |     1 | 200 |
|       3 |     2 | 200 |
|       4 |     1 | 500 |