How do I link the subquery to the main query? - sql

Question

I am having an issue getting blast_seconds to show up as the correct value. In my select subquery I need to get the blast_seconds to show up within the same time as in my main Select statement. When the query is executed Year, Month, ScheduledSeconds, TotalDays and Totaltrucks match up, but blast_seconds column shows the same value through out all the months.
Here is my query:
SELECT DATEPART(YEAR, [Time]) AS [Year]
, DATEPART(MONTH, [Time]) AS [Month]
, SUM(Total) AS ScheduledSeconds
, COUNT(DISTINCT([Time])) AS TotalDays
, COUNT(DISTINCT(Equipment)) AS TotalTrucks
, (
SELECT SUM(CASE
WHEN dbo.reasons.status_id = '298'
THEN (dbo.by_operator_reasons.seconds)
ELSE 0
END)
FROM dbo.reasons
INNER JOIN by_operator_reasons
ON dbo.reasons.id = by_operator_reasons.reason_id
INNER JOIN equipment
ON by_operator_reasons.equipment_id = equipment.id
WHERE reasons.descrip LIKE 'Blast'
AND [Time] BETWEEN '2011-01-01' AND '2012-05-15'
AND by_operator_reasons.deleted_at IS NULL
AND equipment.type = 'Truck'
) AS Blast_Seconds
FROM by_equipment_times
WHERE [Time] BETWEEN '2011-01-01' and '2012-05-15'
AND equipment_type = 'Truck'
GROUP BY DATEPART(YEAR, [Time])
, DATEPART(MONTH, [Time])
ORDER BY DATEPART(YEAR, [Time]) ASC
, DATEPART(MONTH, [Time]) ASC
Here is my current output:
Year Month SchedSec Days TotalTrucks Blast_Seconds
---- ----- -------- ---- ----------- -------------
2011 1 51340448 31 20 4931156
2011 2 51979509 28 22 4931156
2011 3 58845600 31 22 4931156
2011 4 59121967 30 24 4931156
2011 5 66857271 31 25 4931156
2011 6 67306766 30 28 4931156
2011 7 76976358 31 30 4931156
2011 8 80393145 31 30 4931156
2011 9 75556005 30 30 4931156
2011 10 77741205 31 29 4931156
2011 11 75272400 30 29 4931156
2011 12 77691044 31 29 4931156
2012 1 77683752 31 29 4931156
2012 2 72662400 29 29 4931156
2012 3 77574538 31 29 4931156
2012 4 75172177 30 29 4931156
2012 5 37584000 15 29 4931156

Answer 1

The subquery is not corelated to main query, that is it does not depend on it. You need to connect it, and I believe that you want to do it using Time column.
SELECT DATEPART(YEAR, [Time]) AS [Year]
, DATEPART(MONTH, [Time]) AS [Month]
, SUM(Total) AS ScheduledSeconds
, COUNT(DISTINCT([Time])) AS TotalDays
, COUNT(DISTINCT(Equipment)) AS TotalTrucks
, (
SELECT SUM(CASE
WHEN dbo.reasons.status_id = '298'
THEN (dbo.by_operator_reasons.seconds)
ELSE 0
END)
FROM dbo.reasons
INNER JOIN by_operator_reasons
ON dbo.reasons.id = by_operator_reasons.reason_id
INNER JOIN equipment
ON by_operator_reasons.equipment_id = equipment.id
WHERE reasons.descrip LIKE 'Blast'
AND DATEPART(YEAR, [Time]) = DATEPART(YEAR, by_equipment_times.[Time])
AND DATEPART(MONTH, [Time]) = DATEPART(MONTH, by_equipment_times.[Time])
AND by_operator_reasons.deleted_at IS NULL
AND equipment.type = 'Truck'
) AS Blast_Seconds
FROM by_equipment_times
WHERE [Time] BETWEEN '2011-01-01' and '2012-05-15'
AND equipment_type = 'Truck'
GROUP BY DATEPART(YEAR, [Time])
, DATEPART(MONTH, [Time])
ORDER BY DATEPART(YEAR, [Time]) ASC
, DATEPART(MONTH, [Time]) ASC
If you regularly take more than few months it would probably pay off to convert subquery to derived table, grouping by year/month and outer-joining to main query.

Answer 2

This is most likely because you do not tell the
Select SUM(CASE WHEN dbo.reasons.status_id = '298'
then (dbo.by_operator_reasons.seconds) ELSE 0 END....
sub query to get values for respective rows - it just sums everything it finds.
You have to bind sub query to main query - something like
[...]
AND equipment.equipemnt_id_or_something = T1.equipment_id_or_something
) AS Blast_Seconds
FROM by_equipment_times as T1
[...]
Or so I think .... :)
PS.
Names of fields are imaginary.