distinct sum does not distinct values - sqlite

Question

I have 2 tables, reservations and articles:
Reservations
------------------------------
Id | Name | City |
------------------------------
1 | Mike | Stockholm
2 | Daniel | Gothenburg
2 | Daniel | Gothenburg
3 | Andre | Gothenburg (Majorna)
Articles
-------------------------------------------------------------
ArticleId | Name | Amount | ReservationId |
-------------------------------------------------------------
10 | Coconuts | 1 | 1
10 | Coconuts | 4 | 2
11 | Apples | 2 | 2
12 | Oranges | 2 | 3
I want to select Articles Name and the sum of Articles.Amount per Articles.ArticleId and Reservations.City.
My code:
SELECT distinct r.ID,a.Name as ArticleName,
sum(a.Amount) as ArticlesAmount,
substr(r.City,1,3) as ToCityName
FROM Reservations r
INNER JOIN Articles a
on r.Id = a.ReservationId
WHERE a.Name <> ''
GROUP BY ToCityName,a.ArticleId,a.Name
ORDER BY ToCityName ASC
This gives me following result:
Id | ArticleName | ArticlesAmount | ToCityName
2 | Coconuts | 8 | Got
2 | Apples | 4 | Got
3 | Oranges | 2 | Got
1 | Coconuts | 1 | Sto
But i want:
Id | ArticleName | ArticlesAmount | ToCityName
2 | Coconuts | 4 | Got
2 | Apples | 2 | Got
3 | Oranges | 2 | Got
1 | Coconuts | 1 | Sto
Help would be appreciated, and an explanation please :)
Fiddle

Answer 1

Have a look at SQLFiddle
Code:
SELECT distinct r.ID,a.Name as ArticleName,
sum(distinct a.Amount) as ArticlesAmount,
substr(r.City,1,3) as ToCityName
FROM Reservations r
INNER JOIN Articles a
on r.Id = a.ReservationId
WHERE a.Name <> ''
GROUP BY ToCityName,a.ArticleId,a.Name
ORDER BY ToCityName ASC
You want to ensure you sum the amount by the distinct number of times it appears per group.

Answer 2

I had added Articles again to select requested rows again... here is query
SELECT DISTINCT
r.ID,
a.`Name` AS ArticleName,
Articles.Amount,
substr(r.City, 1, 3) AS ToCityName
FROM
Reservations r
INNER JOIN Articles a ON r.Id = a.ReservationId
INNER JOIN Articles ON a.ReservationId = Articles.ReservationId
AND a.ArticleId = Articles.ArticleId
WHERE
a. NAME <> ''
GROUP BY
ToCityName,
a.ArticleId,
a. NAME
ORDER BY
ToCityName ASC