Custom GROUP BY clause - sql

Question

SAMPLE DATA
Suppose I have table like this:
No Company Vendor Code Date
1 C1 V1 C1 2016-03-08
1 C1 V1 C1 2016-03-07
1 C1 V1 C2 2016-03-06
DESIRED OUPUT
Desired output should be:
No Company Vendor Code Date
1 C1 V1 C1 2016-03-08
It should take max Date for No, Company, Vendor (group by these columns). But shouldn't group by Code, It have to be taken for that Date.
QUERY
SQL query like:
.....
LEFT JOIN (
SELECT No_, Company, Vendor, Code, MAX(Date)
FROM tbl
GROUP BY No_, Company, Vendor, Code
) t2 ON t1.Company = t2.Company and t1.No_ = t2.No_
.....
OUTPUT FOR NOW
But I got output for now:
No Company Vendor Code Date
1 C1 V1 C1 2016-03-08
1 C1 V1 C2 2016-03-06
That because Code records are different, but It should take C1 code in this case (because No, Company, Vendor match)
WHAT I'VE TRIED
I've tried to remove Code from GROUP BY clause and use SELECT MAX(Code)..., but this is wrong that because It take higher Code by alphabetic.
Have you ideas how can I achieve It? If something not clear I can explain more.

Answer 1

If you don't have any identity column for your table then each row is identified by all column values combination it has. That brings us weird on statement. It includes all columns we are grouping by and a date column which is max for given tuple (No_, Company, Vendor).
select t1.No_, t1.Company, t1.Vendor, t1.Code, t1.Date
from tbl t1
join (select No_, Company, Vendor, MAX(Date) as Date
from tbl
group by No_, Company, Vendor) t2
on t1.No_ = t2.No_ and
t1.Company = t2.Company and
t1.Vendor = t2.Vendor and
t1.Date = t2.Date
Take a look at this similar question.
Edit
Thank you for an answer, but this returning duplicates. Suppose that there can be rows with equal No, Company, Vendor and Date, some other columns are different, but no care. So with INNER SELECT everything fine, It returning distinct values, but problem accured when joining t1, that because It have multiple values.
Then you might be interested in such tsql constructions as rank or row_number. Take a look at Ullas' answer. Try rank as well as it can give slightly different output which might fit your needs.

Answer 2

You could give a row_number partitioned by No, Vendor and Date and order by descending order of date.
Query
;with cte as (
select rn = row_number() over(
partition by [No], Company, Vendor
order by [Date] desc
), *
from tbl
)
select [No], Company, Vendor, Code, [Date] from cte
where rn = 1;

Answer 3

If 1 date only can have 1 record, then you can Query it by search the max date first, then check it.
select No_, Company, Vendor, Code, Date
FROM tbl
where Date in
(select MAX(Date) from tbl GROUP BY No_, Company, Vendor)
if there is more than 1 row that could have the same date, then you could use partition
with cte as
(
select *, ROW_NUMBER() over(partition by No_, Company, Vendor order by Date DESC) as rn
from tbl
)
select No_, Company, Vendor, Code, Date
from cte
where rn=1

Answer 4

A Common Table Expression will do it for you.
WITH cte(N,C,V,D)
AS
(
SELECT t1.[No]
,t1.[Company]
,t1.[Vendor]
,MAX(t1.[Date])
FROM [MyTest] t1
GROUP BY t1.[No]
,t1.[Company]
,t1.[Vendor]
)
SELECT N,C,V,t2.Code,D
FROM cte c
INNER JOIN MyTest t2 ON c.N = t2.No AND c.C = t2.Company AND c.V = t2.Vendor AND c.D = t2.Date