When I run the following SQL statement:
SELECT MAX(SUM(TIME))
FROM downloads
GROUP BY SSN
It returns the maximum sum value of downloads by a customer, however if I try to find the social security number that that max value belongs to by adding it to the select statement:
SELECT SSN, MAX(SUM(TIME))
FROM downloads
GROUP BY SSN
I get the following error:
not a single-group group function
I do not understand why it is throwing this error. A google search came up with the following action:
Drop either the group function or the individual column expression from the SELECT list or add a GROUP BY clause that includes all individual column expressions listed
From what I think this is saying - dropping the group function makes the sum value invalid - droping the individual column expression (SSN) will just give me the max sum - not sure about that third part.
Could anyone guide in the right direction?
-Tomek
EDIT: TIME in this database refers to the number of times downloaded