Finding the next occurrence of a value in a table - sql

Question

Sorry in advance if this has already been covered.
I am working on a database which isnt particularly well structured but it is owned by a third party and cannot be changed.
I need some assistance with t-sql in find the next occurrence of a value within the table and return records based on the result. Let me first explain the data. I have simplified this to make it easier to understand.
Polref Effective Date Transaction Type Suffix Value
ABCD1 01/06/2010 New Bus 1 175.00
ABCD1 01/06/2011 Ren 2 200.00
ABCD1 19/08/2011 Adjust 3 50.00
ABCD1 23/04/2012 Adjust 4 50.00
ABCD1 01/06/2012 Ren 5 275.00
So if I ran my query for 2011, the code would need to return in this example rows with suffix 2,3 and 4. So what I have been trying to do is find the first suffix of a New Bus or Ren for the specified year and then finding the next suffix for a New Bus or Ren for the same polref and then using those two suffix values to limit my recordset. It aint working!!
I cant use MAX() as transactions for 2013 have already been added to the system to I would get more records than I actually need.
There result I should be expecting for this example data would be:
ABCD1 300.00
Any help would be greatly appreciated.
To answer another question, If I select 2011 as my year to run the report, there should only be one New Bus or Ren transaction for 2011 so if its a New Bus transaction, the next main transaction will be a Ren, if its a Ren then the next main transaction will be a Ren. Again in my example below, if I run for 2011, it should find the Ren from 01/06/2011 so I want to return that Ren and the two Adjust records.
Sorry, I've not used this forum before so apologies if I was a little vague.
The table I am using has many polrefs so I need this code to calculate totals for all polrefs that fall within the date range. Some polrefs may only have one row, a New Bus, some will have many rows depending on how many adjustments have been made throughout the year of the policy

Answer 1

Partial answer:
This query:
declare #t table (PolRef char(5) not null, EffectiveDate date not null,TransactionType varchar(10) not null,Suffix int not null,Value decimal(10,2) not null)
insert into #t (Polref,EffectiveDate,TransactionType,Suffix,Value) values
('ABCD1','20100601','New Bus',1,175.00),
('ABCD1','20110601','Ren',2,200.00),
('ABCD1','20110819','Adjust',3,50.00),
('ABCD1','20120423','Adjust',4,50.00),
('ABCD1','20120601','Ren',5,275.00)
;With StartTransactions as (
select PolRef,Suffix,ROW_NUMBER() OVER (PARTITION BY PolRef ORDER BY Suffix) rn
from #t where TransactionType in ('New Bus','Ren')
), Periods as (
select st1.PolRef,st1.Suffix as StartSuffix,st2.Suffix as EndSuffix
from
StartTransactions st1
left join
StartTransactions st2
on
st1.PolRef = st2.PolRef and
st1.rn = st2.rn - 1
)
select
p.PolRef,t2.EffectiveDate,SUM(t.Value) as Total
from
Periods p
inner join
#t t
on
p.PolRef = t.PolRef and
p.StartSuffix <= t.Suffix and
(p.EndSuffix > t.Suffix or
p.EndSuffix is null)
inner join
#t t2
on
p.PolRef = t2.PolRef and
t2.Suffix = p.StartSuffix
group by
p.PolRef,t2.EffectiveDate
Groups each set of transactions based on each successive Ren or New Bus transaction:
PolRef EffectiveDate Total
------ ------------- ---------------------------------------
ABCD1 2010-06-01 175.00
ABCD1 2011-06-01 300.00
ABCD1 2012-06-01 275.00
From that, it should be trivial to e.g. select out only the ones you're interested in from a particular year. But your question is still vague on some specifics, so I'm not taking it any further at this point.