TSQL Join on Tables with Multiple Counts - sql

Question

I have a table that I am trying to get 2 different counts from the same data using 2 left joins.
For whatever reason, it is duplicating the data and providing an incorrect result and I am not sure why.
This is the query that I have so far which I thought would be working:
DECLARE #locale INT = '14'
SELECT TOP 50
E.[DepartmentDesc] AS department,
COUNT(N.[nomineeQID]) AS totalNominations,
COUNT(S.[subQID]) AS totalSubmissions,
COUNT(N.[nomineeQID]) + COUNT(S.[subQID]) AS total
FROM
employees AS E
LEFT JOIN
submissions AS S ON E.[qid] = S.[subQID] AND S.[statusID] = 3
AND S.[locationID] = #locale
LEFT JOIN
submissions AS N ON E.[qid] = N.[nomineeQID] AND N.[statusID] = 3
AND N.[locationID] = #locale
GROUP BY
E.[DepartmentDesc]
ORDER BY
totalNominations DESC
Here is a SQL Fiddle of the data: http://sqlfiddle.com/#!3/4e6b5/1
The result should be the following but it is providing skewed numbers:
Total Nominations should be 3
Total Submissions should be 2
Total should be 5
I have a feeling its close but the math is just not cooperating!
Any ideas?

Answer 1

You are getting a cartesian product for each department. The simplest fix to your query is to use count(distinct):
COUNT(DISTINCT N.[nomineeQID]) AS totalNominations,
COUNT(DISTINCT S.[subQID]) AS totalSubmissions,
COUNT(DISTINCT N.[nomineeQID]) + COUNT(DISTINCT S.[subQID]) AS total
A more correct fix is to do the aggregations in subqueries before doing the join.
EDIT:
Because of the duplications problem, use SubmissionId instead:
COUNT(DISTINCT N.SubmissionId) AS totalNominations,
COUNT(DISTINCT S.SubmissionId) AS totalSubmissions,
COUNT(DISTINCT N.SubmissionId) + COUNT(DISTINCT S.SubmissionId) AS total

Answer 2

Try this:
DECLARE #locale INT = '14'
select TOP 50 t.department, sum(t.totalSubmissions),
sum(t.totalNominations), sum(t.total)
from
(SELECT
E.[DepartmentDesc] AS department,
(select COUNT(S.[subQID])
from submissions AS S
where E.[qid] = S.[subQID]
AND S.[statusID] = 3
AND S.[locationID] = #locale) AS totalSubmissions,
(select COUNT(N.[nomineeQID])
from submissions AS N
where E.[qid] = N.[nomineeQID]
AND N.[statusID] = 3
AND N.[locationID] = #locale) AS totalNominations,
(select COUNT(S.[subQID])
from submissions AS S
where E.[qid] = S.[subQID]
AND S.[statusID] = 3
AND S.[locationID] = #locale) +
(select COUNT(N.[nomineeQID])
from submissions AS N
where E.[qid] = N.[nomineeQID]
AND N.[statusID] = 3
AND N.[locationID] = #locale) AS total
FROM employees AS E
where exists(
select 'submission'
from submissions AS S
where E.[qid] = S.[subQID]
AND S.[statusID] = 3
AND S.[locationID] = #locale
) or
exists(
select 'nomination'
from submissions AS N
where E.[qid] = N.[nomineeQID]
AND N.[statusID] = 3
AND N.[locationID] = #locale
)
) as t
group by t.department
ORDER BY sum(t.totalNominations) DESC
Go to SqlFiddle