SQL Case MAX WHEN LIKE - sql

Question

I would like to create a case statement or a rank over statement for a particular outlier case I have.
I am not sure how to write a case statement utilizing CASE (pseudo code)
WHEN MAX Total_Revenue COMPANY like 'ABC%'
else COMPANY
i have tried rank over, but it is not working:
,RANK() OVER(COMPANY LIKE 'DEF%' ORDER BY Total_Revenue DESC) AS grp
Current table:
Company Total_Revenue
ABC 10
DEF1 25 --This row will NOT be selected as its less than
DEF2 35 -- this row will be kept
GHI3 65
JKL9 100
Ouput table:
Company Total_Revenue
ABC 10
DEF2 35 --kept
GHI3 65
JKL9 100

Answer 1

There's quite a few ways to do what it seems like you are after:
Using a subquery to find max revenue for each comp:
SELECT Company, Total_Revenue
FROM myTable
INNER JOIN
(
SELECT Left(Company, 3) as leftcomp,
max(Total_Revenue) as maxTotalRevenue
FROM mytable
GROUP BY Left(Company, 3)
) mt
ON Left(myTable.Company, 3) = mt.leftcomp
AND myTable.Total_Revenue = mt.maxTotalRevenue;
Window function that is later filtered by Where:
SELECT *
FROM
(
SELECT Company,
Total_Revenue,
MAX(Total_Revenue) OVER (PARTITION BY Left(Company, 3)) as maxTotalRevenue
FROM myTable
) mt
WHERE Total_Revenue = maxTotalRevenue;
Correlated subquery in the WHERE clause:
SELECT *
FROM myTable mt1
Where Total_Revenue =
(
SELECT max(total_revenue)
FROM myTable
WHERE Left(myTable.Company, 3) = Left(mt1.Company, 3)
);
SQLFiddle here

Answer 2

You seems want row_number() function :
SELECT t.*
FROM (SELECT *, ROW_NUMBER() OVER (PARTITION BY LEFT(Company, 3) ORDER BY Total_Revenue DESC) AS Seq
FROM table t
) t
WHERE Seq = 1;

Answer 3

This is what you want ?
select * from t
where
Company not in (
select Company from t where Company like '%DEF%' order by Company desc offset 1
)

Answer 4

use aggregate function max() and sub-query
select * from Yourtable t1
where t1.Total_Revenue in (
select max(T.Total_Revenue ) as Total_Revenue from
(
select case when Company like'%DEF%' then 'DEF'
else Company end as Company ,
Total_Revenue from Yourtable
) as T
group by T.Company
)
http://sqlfiddle.com/#!18/e896c/5
Company Total_Revenue
ABC 10
DEF2 35
GHI3 65
JKL9 100