SQL：最大值未选择最大值

Question

My SQL Code is the following:

Select Model,Max(Price) FROM Printer GROUP BY Model ORDER BY Max(Price) DESC;

It should return the following:

MODEL   MAX PRICE
3007    899
3003    899

However, it instead returns this:

MODEL   MAX PRICE
3007    899
3003    899
3002    139
3004    120
3006    100
3005    99

What am I doing wrong? I tried changing or removing Order by and the like, but it did not fix my problem.

Answer 1

If you only want the maximum priced rows, then you need to limit the number of rows. You seem to want rank() :

SELECT Model, max_price
FROM (SELECT Model, MAX(Price) as max_price,
             RANK() OVER (ORDER BY MAX(PRICE) DESC NULLS LAST) as seqnum
      FROM Printer p
      GROUP BY Model
     ) p
WHERE seqnum = 1;

Answer 2

This is a cleaner method to get what I wanted

SELECT 
Model, 
Price
FROM
Printer
WHERE price = (SELECT MAX(PRICE) FROM Printer)
;

Answer 3

If you are using Oracle 12.1 or later:

select model, max(price) from printer
group by model
order by max(price) desc
fetch first row with ties;