Question

What I am trying to achieve is to get the rows having the maximum value from a table of the following form:

A | B | Ratio 
0 | 1 | 1.0
1 | 2 | 1.0
2 | 3 | 1.0
3 | 4 | 0.33
4 | 5 | 0.25

I am trying to display only rows containing the maximum value (in this case 1.0). May be I am not doing this right. I have a query of the form:

SELECT A,B,C 
FROM (---Long Sub Query--- Aliased as Full_Table)
WHERE RATIO=(SELECT MAX(RATIO) FROM Full_Table);

But Full_Table cannot be referenced from the second sub-query. There are some rows having the same maximum value which is the reason I was using this query. Is there a better construct to achieve this? In the worst case, I have to replace the second Full_Table by the entire long query but I’m hoping there is a better way to do this.

Answer 1

You can use a Common Table Expression:

WITH Full_Table AS (---Long Sub Query---)
SELECT A,B,C 
FROM Full_Table
WHERE RATIO=(SELECT MAX(RATIO) FROM Full_Table);