Problem: I want to find the % of people who's last login date is the same as their registration date. Basically I want to find out who created a account and never logged in again. I want to put this into a percentage taking every instance of lastlogindate = registrationdate and dividing that by the total amount of users signed up for each month. CODE:	SELECT 	count (((userdata.userid))) as [distinct users]	,datename(year,saleschannel.createddate) as [year]	,datename(month,saleschannel.createddate) as [month]	,count(saleschannel.saleschannelid) AS [# of saleschannels]	,((count(*) /cast((count (distinct(userdata.userid)))as float)) * 100) as [% sales channels]		FROM saleschannel	INNER JOIN company on company.companyid = saleschannel.companyid 	INNER JOIN userdata on userdata.companyid = company.companyid and roleid = 1 AND company.createduserid = userdata.userid	--INNER JOIN product on product.companyid = saleschannel.companyid	--WHERE company.registrationdate = userdata.lastlogindate 		GROUP BY  month(saleschannel.createddate)	, year(saleschannel.createddate)	, datename(year,saleschannel.createddate)	,datename(month,saleschannel.createddate)		order by year(saleschannel.createddate),month(saleschannel.createddate)
It outputs this [distinct users]	[year]	[month]	[# of saleschannels]	[% sales channels]7	2012	June	7	1402	2012	July	2	2002	2012	October	2	2008	2013	February	8	4007	2013	March	7	35011	2013	April	11	157.14285714285718	2013	May	18	257.1428571428576	2013	June	6	3001	2013	July	1	1003	2013	August	3	3003	2013	September	3	1502	2013	October	2	20016	2014	January	16	228.57142857142924	2014	February	24	342.85714285714314	2014	March	14	28010	2014	April	10	25053	2014	May	53	311.76470588235316	2014	June	16	177.777777777778An obvious fix would be to add in WHERE company.registrationdate = userdata.lastlogindate 
But doing so would only show the cases of users not logging on and would ignore the other data that I have.[distinct users]	[year]	[month]	[# of saleschannels]	[% sales channels]2	2012	June	2	1004	2013	May	4	1002	2014	February	2	2002	2014	May	2	2005	2014	June	5	125This is fine but I need to see the other months also, not just the months where registrationdate = lastlogindateIve tried doing a subquery butI had issues with keeping the same structure that the main query had using the GROUP BY statement.Sorry if this was long but wanted it to be thorough