Postgres中的总数

Question

I have a query to find the number of logins by a given user who has logged in more than once per day:

SELECT login_id, count(*) FROM login_test GROUP BY login_id HAVING count(*) > 1;

How can I get the sum of all the multiple logons? I've tried something like:

SELECT SUM(SELECT count(*) FROM login_test GROUP BY login_id HAVING count(*) > 1);

with no luck.

Answer 1

Use a derived table:

SELECT sum(count)
FROM (
    SELECT login_id, count(*) 
    FROM login_test 
    GROUP BY login_id 
    HAVING count(*) > 1
    ) s;

Answer 2

  Select sum(t.cnt) as agg_count
   from
  (Select count(*) as cnt
         from table1
          Group by id having count(*) > 1
  ) t