Select Max revenue by date and client - sql

Question

The following is sample data from my table:
Rev Date Client
1890 2015-11-20 xyz
1536.28 2017-10-27 AAA
934.84 2017-10-27 AAA
919.592 2017-03-22 AAA
760.985 2014-11-25 xyz
I need to select the day with the highest revenue for each client.
I have the following query but it selects the max revenue for each day by client rather than just the day with the highest rev per client
SELECT TOP 1 max(rev)/1000 AS Rev, date, client FROM table1 GROUP BY date, client

Answer 1

Common question. I presume that Rev is already totaled per day and we're just picking out the highest row. If there are ties you could use dense_rank() instead.
select * from (
select *, row_number() over (partition by Client order by Rev desc) as rn
from table1
) t
where rn = 1;

Answer 2

One option is to use the the WITH TIES clause in concert with Row_Number()
Example
Select top 1 with ties *
From YourTable
Order By Row_Number() over (Partition By Client Order By Rev Desc)

Answer 3

Setup:
DECLARE #data TABLE
(
Rev money
, [Date] date
, Client nvarchar(10)
)
INSERT INTO #data
VALUES
(1890, '2015-11-20', 'xyz')
,(1536.28, '2017-10-27', 'AAA')
,(934.84, '2017-10-27', 'AAA')
,(919.592, '2017-03-22', 'AAA')
,(760.985, '2014-11-25', 'xyz')
Query:
SELECT Client
, t.[Date]
FROM
(
SELECT Client
, [Date]
, SUM(Rev) AS [TotalRev]
, ROW_NUMBER() OVER (PARTITION BY Client ORDER BY SUM(Rev) DESC) AS RN
FROM #data
GROUP BY Client, [Date]
) AS t
WHERE t.RN = 1
Results:
Client Date
====================
AAA 2017-10-27
xyz 2015-11-20

Answer 4

My understanding michaelg's question is per day the highest revenue transactions, so:
select * from (
select *, row_number() over (partition by [date] order by Rev desc) as rn
from ##table1
) t
where rn = 1;
If you want total amount of your client, you have group all rev into subquery.
Please try your script in my T-SQL Code playground https://sqleditor.net/q/B19r72H_f

Answer 5

I would use CROSS APPLY for this.
SELECT DISTINCT ca.*
FROM table1 t
CROSS APPLY (SELECT TOP 1 *
FROM table1
WHERE Client = t.Client
ORDER BY Rev DESC) ca
It's cleaner if you already have a Client table that has unique ids.
SELECT ca.Rev, ca.Date, c.Client
FROM Client c
CROSS APPLY (SELECT TOP 1 Rev, Date
FROM table1
WHERE Client = c.Client
ORDER BY Rev DESC) ca