How to efficiently match on dates in SQL Server? - sql-server

Question

I am trying to return the first registration for a person based on the minimum registration date and then return full information. The data looks something like this:
Warehouse_ID SourceID firstName lastName firstProgramSource firstProgramName firstProgramCreatedDate totalPaid totalRegistrations
12345 1 Max Smith League Kid Hockey 2017-06-06 $100 3
12345 6 Max Smith Activity Figure Skating 2018-09-26 $35 1
The end goal is to return one row per person that looks like this:
Warehouse_ID SourceID firstName lastName firstProgramSource firstProgramName firstProgramCreatedDate totalPaid totalRegistrations
12345 1 Max Smith League Kid Hockey 2017-06-06 $135 4
So, this would aggregate the totalPaid and totalRegistrations variables based on the Warehouse_ID and would pull the rest of the information based on the min(firstProgramCreatedDate) specific to the Warehouse_ID.
This will end up in Tableau, so what I've recently tried ignores aggregating totalPaid and totalRegistrations for now (I can get that in another query pretty easily). The query I'm using seems to work, but it is taking forever to run; it seems to be going row by row for >50,000 rows, which is taking forever.
select M.*
from (
select Warehouse_ID, min(FirstProgramCreatedDate) First
from vw_FirstRegistration
group by Warehouse_ID
) B
left join vw_FirstRegistration M on B.Warehouse_ID = M.Warehouse_ID
where B.First in (M.FirstProgramCreatedDate)
order by B.Warehouse_ID
Any advice on how I can achieve my goal without this query taking an hour plus to run?

Answer 1

A combination of the ROW_NUMBER windowing function, plus the OVER clause on a SUM expression should perform pretty well.
Here's the query:
SELECT TOP (1) WITH TIES
v.Warehouse_ID
,v.SourceID
,v.firstName
,v.lastName
,v.firstProgramSource
,v.firstProgramName
,v.firstProgramCreatedDate
,SUM(v.totalPaid) OVER (PARTITION BY v.Warehouse_ID) AS totalPaid
,SUM(v.totalRegistrations) OVER (PARTITION BY v.Warehouse_ID) AS totalRegistrations
FROM
#vw_FirstRegistration AS v
ORDER BY
ROW_NUMBER() OVER (PARTITION BY v.Warehouse_ID
ORDER BY CASE WHEN v.firstProgramCreatedDate IS NULL THEN 1 ELSE 0 END,
v.firstProgramCreatedDate)
And here's a Rextester demo: https://rextester.com/GNOB14793
Results (I added another kid...):
+--------------+----------+-----------+----------+--------------------+------------------+-------------------------+-----------+--------------------+
| Warehouse_ID | SourceID | firstName | lastName | firstProgramSource | firstProgramName | firstProgramCreatedDate | totalPaid | totalRegistrations |
+--------------+----------+-----------+----------+--------------------+------------------+-------------------------+-----------+--------------------+
| 12345 | 1 | Max | Smith | League | Kid Hockey | 2017-06-06 | 135.00 | 4 |
| 12346 | 6 | Joe | Jones | Activity | Other Activity | 2017-09-26 | 125.00 | 4 |
+--------------+----------+-----------+----------+--------------------+------------------+-------------------------+-----------+--------------------+
EDIT: Changed the ORDER BY based on comments.

Answer 2

Try to use ROW_NUMBER() with PARTITIYION BY.
For more information please refer to:
https://learn.microsoft.com/en-us/sql/t-sql/functions/row-number-transact-sql?view=sql-server-2017