Postgres: select the sum of values and then sum this again

Question

I tried a lot but can´t find the right way. If I select values in Postgres and sum them it looks like this:

SELECT name,sum(size) as total
FROM mytable group         


        

Answer 1

If you want all results with the same SELECT, you could do something like

SELECT 
  'grand total' AS name, 
   sum(size) AS sum 
FROM 
  mytable 
UNION ALL 
SELECT 
  name, 
  sum(size) AS sum 
FROM 
  mytable 
GROUP BY 
  name;

Hope it helps…