I gather its a marketing tool.

So you get a group of customers who bought in Year 2010 Q1 and you track the same groups spent through the years.

2010 Q2 - £50 AVG

2010 Q3 - £30

2010 Q4 - £25

so each month a new group appears and you track them.

YearQInitial#Q1Q2Q3Q4Q5Q6

20134$239 171

20133$338 19848

20132$268 2241515

20124$203 1608611

20123$229 20630846

20122$273 2021489512

20121$254 322241017102215

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So far I am getting the accounts by year and quarter and think to use that data in a CTE??

select

o.[account_id]

,orderyear

,orderquarter

from

[dbo].[orders] o

inner join [dbo].[orderlines] ol on o.[order_id] = ol.[order_id]

cross apply(values(year(o.[ship_date]))) as a1(orderyear)

cross apply(values(DatePart(quarter,(o.[ship_date])))) as a2(orderquarter)

where

product_code like ('ll%') and ship_date = (select min(ship_date) from [dbo].[orders] mo where mo.[order_id] = ol.order_id)

and total_value>0 AND order_status NOT LIKE 'return%' AND order_status NOT LIKE 'cancel%' AND order_status NOT LIKE 'freeze%'

Thanks