Question

I have a temp table I am creating a query off of in the following format. That contains a record for every CustomerID, Year, and Month for several years.

#T

Customer | CustomerID | Year | Month

ex.

Foo | 12345 | 2008 | 12   Foo | 12345 | 2008 | 11   Bar | 11224 | 2007 | 7 

When I join this temp table to another table of the following format I get many more results than I am expecting.

Event

EventID | CustomerID | DateOpened

ex.

1100 | 12345 | '2008-12-11 10:15:43' 1100 | 12345 | '2008-12-11 11:25:17' 

I am trying to get a result set of the count of events along with the Customer, Year, and Month like this.

SELECT COUNT(EventID), Customer, Year, Month FROM [Event]  JOIN #T ON [Event].CustomerID = #T.CustomerID WHERE [Event].DateOpened BETWEEN '2008-12-01' AND '2008-12-31' GROUP BY Customer, Year, Month ORDER BY Year, Month 

I am getting a record for every Year and Month instead of only for December 2008.

Answer 1

You’re specifying the date on the event table but not on the join — so it’s joining all records from the temp table with a matching customerid.

Try this:

SELECT COUNT(e.EventID), T.Customer, T.Year, T.Month FROM [Event] e INNER JOIN #T T ON (   T.CustomerID = e.CustomerID and    T.Year = year(e.DateOpened) and    T.Month = month(e.DateOpened)    )  WHERE T.Year = 2008    and T.Month = 12  GROUP BY T.Customer, T.Year, T.Month ORDER BY T.Year, T.Month