How to obtain summary summation when GROUP BY is not working?

I have data with the columns

• User_id (char)

• filename (char)

• filesize (numeric)

Every user_id has more than 5 files to it’s name, of different filesize values.

Problem statement: I want to have a summary of this table, with columns, User_id, Filesize, where it shows the total size occupied by each user id.

It tried Group By user id, in Proc SQL,

proc sql;
CREATE TABLE want as 
SELECT user_id, filesize 
FROM have
GROUP BY user_id;
QUIT;

but it throws a warning that says

A GROUP BY clause has transformed into an ORDER BY clause because neither the SELECT clause nor the optional HAVING clause of the associated table-expression referenced a summary function.

Are there other ways to do this in SAS?

Answer

proc sql;
CREATE TABLE want as 
SELECT user_id, SUM(filesize) as TotalFileSize 
FROM have
GROUP BY user_id;
QUIT;