Your query only extracts the month integer from a date, it does not floor it to the month. The equivalent for sql server is this ugly thing: select dateadd(month,datediff(month,0,getdate()),0)
We are on SQL server 2014. I have had a query go from 2-3 hours down to 7 minutes by replacing left joins with subselects within the query for instance (and yes all the indices are in place as recommended by sql server query planer)
The one with a insert based on a query on the same table I have never managed to run at all and I have to use a temporary table as an intermediary instead.
