SQL counts with left join - sql-server

Question

On my Microsoft SQL Server 2016 database I'm trying to determine how many labs (Lab_Space table) have had an assessment (EHS_Assessment_Audit table) done within the last year, grouped by location (Locations table). It's common to have more than one assessment done per year per lab.
Everything I've tried so far results in more "done" counts than labs. For example:
WITH cte AS
(
SELECT DISTINCT
Lab_Space_Id
FROM
EHS_Assessment_Audit
WHERE
Audit_Date >= DATEADD(year, -1, GETDATE())
)
SELECT
l.Site_Name, l.Campus_Name,
COUNT(DISTINCT s.id) Total,
SUM(CASE WHEN a.Lab_Space_ID IS NOT NULL THEN 1 ELSE 0 END) Audited
FROM
Lab_Space s
LEFT OUTER JOIN
cte a ON s.id = a.Lab_Space_Id
JOIN
Locations l ON l.Building_Code = s.Building_Code
GROUP BY
l.Site_Name, l.Campus_Name
ORDER BY
l.Site_Name, l.Campus_Name
The cte there should get me a unique list of labs that have had an assessment done, and then I'm trying to count that grouped by location. I'm ending up with output though where it'll say there are 178 total and 1080 audited for a single site/campus combo.

Answer 1

I think using a CTE in this case is going to be more trouble than it's worth. A subquery is going to be easier to read and modify. For example:
SELECT
l.Site_Name,
l.Campus_Name,
COALESCE(b.NumAudits, 0) as NumTotalAudits,
COALESCE(b.NumLabs, 0) as AuditedLabs
FROM Locations l
LEFT JOIN (
SELECT s.Building_Code, COUNT(*) as NumAudits, COUNT(DISTINCT s.Lab_Space_Id) as NumLabs
FROM Lab_Space s
INNER JOIN EHS_Assessment_Audit a ON s.Lab_Space_Id = a.Lab_Space_Id
WHERE a.Audit_Date >= DATEADD(year, -1, GETDATE())
GROUP BY s.Building_Code
) as b ON l.Building_Code = b.Building_Code
With overly simplistic temp tables and example data:
CREATE TABLE #EHS_Assessment_Audit (Lab_Space_Id int, Audit_Date datetime)
CREATE TABLE #Lab_Space (Lab_Space_Id int, Building_Code int)
CREATE TABLE #Locations (Location_Id int, Building_Code int, Site_Name nvarchar(30), Campus_Name nvarchar(30))
INSERT INTO #Locations VALUES (1, 1, 'Location1', 'Campus1'), (2, 2, 'Location2', 'Campus2')
INSERT INTO #Lab_Space VALUES (1, 1), (2, 1), (3, 2), (4, 2)
INSERT INTO #EHS_Assessment_Audit VALUES (1, '2018-10-11'), (1, '2018-09-11'), (2, '2018-10-11'), (3, '2015-10-11')
SELECT * FROM #Locations
SELECT * FROM #Lab_Space
SELECT * FROM #EHS_Assessment_Audit
SELECT
l.Site_Name,
l.Campus_Name,
COALESCE(b.NumAudits, 0) as NumTotalAudits,
COALESCE(b.NumLabs, 0) as AuditedLabs
FROM #Locations l
LEFT JOIN (
SELECT s.Building_Code, COUNT(*) as NumAudits, COUNT(DISTINCT s.Lab_Space_Id) as NumLabs
FROM #Lab_Space s
INNER JOIN #EHS_Assessment_Audit a ON s.Lab_Space_Id = a.Lab_Space_Id
WHERE a.Audit_Date >= DATEADD(year, -1, GETDATE())
GROUP BY s.Building_Code
) as b ON l.Building_Code = b.Building_Code