TSQL - Return recent date - sql-server

Question

Having issues getting a dataset to return with one date per client in the query.
Requirements:
Must have the recent date of transaction per client list for user
Will need have the capability to run through EXEC
Current Query:
SELECT
c.client_uno
, c.client_code
, c.client_name
, c.open_date
into #AttyClnt
from hbm_client c
join hbm_persnl p on c.resp_empl_uno = p.empl_uno
where p.login = #login
and c.status_code = 'C'
select
ba.payr_client_uno as client_uno
, max(ba.tran_date) as tran_date
from blt_bill_amt ba
left outer join #AttyClnt ac on ba.payr_client_uno = ac.client_uno
where ba.tran_type IN ('RA', 'CR')
group by ba.payr_client_uno
Currently, this query will produce at least 1 row per client with a date, the problem is that there are some clients that will have between 2 and 10 dates associated with them bloating the return table to about 30,000 row instead of an idealistic 246 rows or less.
When i try doing max(tran_uno) to get the most recent transaction number, i get the same result, some have 1 value and others have multiple values.
The bigger picture has 4 other queries being performed doing other parts, i have only included the parts that pertain to the question.
Edit (2011-10-14 # 1:45PM):
select
ba.payr_client_uno as client_uno
, max(ba.row_uno) as row_uno
into #Bills
from blt_bill_amt ba
inner join hbm_matter m on ba.matter_uno = m.matter_uno
inner join hbm_client c on m.client_uno = c.client_uno
inner join hbm_persnl p on c.resp_empl_uno = p.empl_uno
where p.login = #login
and c.status_code = 'C'
and ba.tran_type in ('CR', 'RA')
group by ba.payr_client_uno
order by ba.payr_client_uno
--Obtain list of Transaction Date and Amount for the Transaction
select
b.client_uno
, ba.tran_date
, ba.tc_total_amt
from blt_bill_amt ba
inner join #Bills b on ba.row_uno = b.row_uno
Not quite sure what was going on but seems the Temp Tables were not acting right at all. Ideally i would have 246 rows of data, but with the previous query syntax it would produce from 400-5000 rows of data, obviously duplications on data.

Answer 1

I think you can use ranking to achieve what you want:
WITH ranked AS (
SELECT
client_uno = ba.payr_client_uno,
ba.tran_date,
be.tc_total_amt,
rnk = ROW_NUMBER() OVER (
PARTITION BY ba.payr_client_uno
ORDER BY ba.tran_uno DESC
)
FROM blt_bill_amt ba
INNER JOIN hbm_matter m ON ba.matter_uno = m.matter_uno
INNER JOIN hbm_client c ON m.client_uno = c.client_uno
INNER JOIN hbm_persnl p ON c.resp_empl_uno = p.empl_uno
WHERE p.login = #login
AND c.status_code = 'C'
AND ba.tran_type IN ('CR', 'RA')
)
SELECT
client_uno,
tran_date,
tc_total_amt
FROM ranked
WHERE rnk = 1
ORDER BY client_uno
Useful reading:
Ranking Functions (Transact-SQL)
ROW_NUMBER (Transact-SQL)
WITH common_table_expression (Transact-SQL)
Using Common Table Expressions