T-SQL (Azure) Only shows 2 results instead of 3 - sql

Question

Hi i am extending a query and i have the following problem, i have in a table 3 users and they are connected (joined) with other tables, now in these tables the user can or can not have data, depending on their actions.
SELECT
COALESCE (credit.received, 0) AS CreditReceived,
COALESCE (purchase.used, 0) AS CreditUsed,
COALESCE (purchase.NumberOfPurchase, 0) AS NumberOfPurchase,
COALESCE (credit.received, 0) - COALESCE (purchase.used, 0) AS UserCredit,
dbo.[User].id_user,
dbo.[User].name,
dbo.[User].town,
dbo.[User].country
FROM (SELECT DISTINCT id_user
FROM dbo.UserCredit
UNION
SELECT DISTINCT id_user
FROM dbo.UserPurchase) AS users
INNER JOIN
dbo.[User] ON users.id_user = dbo.[User].id_user
LEFT OUTER JOIN
(SELECT
id_user,
SUM(creditRecieved) AS received
FROM
dbo.UserCredit AS UserCredit_1
GROUP BY id_user) AS credit
ON users.id_user = credit.id_user
LEFT OUTER JOIN
(SELECT
id_user,
SUM(creditUsed) AS used,
COUNT(creditUsed) AS NumberOfPurchase
FROM
dbo.UserPurchase AS UserPurchase_1
GROUP BY id_user) AS purchase
ON users.id_user = purchase.id_user
The information comes from these tables;
TABLE dbo.user
id_user name town country
----------- ----------- -------------- -------------
1 George New York USA
2 Lucas San Diego GB
3 Steven San Fran Germany
TABLE dbo.UserCredit
id id_user creditRecieved PurchasePrice
----------- ----------- -------------- -------------
1 1 150 750
2 1 25 100
3 2 65 15
TABLE dbo.UserPurchase
id id_user creditUsed date
----------- ----------- ----------- -----------
1 1 175 NULL
2 2 3 NULL
3 2 2 NULL
What i get is only the result of the two first user_id's and the third one (steven) is not shown in the results, i guess it is because the id's dont exist in the other two tables, but that i was hoping would be fixed with the COALESCE and the four of them would be set to 0. What am i doing wrong?

Answer 1

You don't need the derived table "users." It doesn't contain all the userid's and is unnecessary. Remove that and left join to your user table instead and it should work.

Answer 2

By replacing the first DISTINCT with the dbo.[User] instead of the dbo.UserCredit it gave me the right results; All users in the overview with credit or no credit, thanks to the COALESCE :)
SELECT
COALESCE (credit.received, 0) AS CreditReceived,
COALESCE (purchase.used, 0) AS CreditUsed,
COALESCE (purchase.NumberOfPurchase, 0) AS NumberOfPurchase,
COALESCE (credit.received, 0) - COALESCE (purchase.used, 0) AS UserCredit,
dbo.[User].id_user,
dbo.[User].name,
dbo.[User].town,
dbo.[User].country
FROM (SELECT DISTINCT id_user
FROM dbo.[User]
UNION
SELECT DISTINCT id_user
FROM dbo.UserPurchase) AS users
INNER JOIN
dbo.[User] ON users.id_user = dbo.[User].id_user
LEFT OUTER JOIN
(SELECT
id_user,
SUM(creditRecieved) AS received
FROM
dbo.UserCredit AS UserCredit_1
GROUP BY id_user) AS credit
ON users.id_user = credit.id_user
LEFT OUTER JOIN
(SELECT
id_user,
SUM(creditUsed) AS used,
COUNT(creditUsed) AS NumberOfPurchase
FROM
dbo.UserPurchase AS UserPurchase_1
GROUP BY id_user) AS purchase
ON users.id_user = purchase.id_user