Referring to a select aggregate column alias in the having clause in Postgres

Question

I\'m migrating from MySQL to Postgres. In MySQL I can use

select sum(clicks) c from table where event_date >= \'1999-01-01\' 
group by keyword_id 
having          


        

Answer 1

Is there a setting in Postgres that will allow it to use column aliases in the having clause?

No. Implementations that allow references to SELECT-list entries in HAVING are going outside the standard.

You should use a subquery, e.g.

select
  c
from (
  select 
    sum(clicks) c
  from table
  where event_date >= '1999-01-01'
  group by keyword_id 
) x
where c > 10;

... or repeat the aggregate.

Answer 2

You can use WITH Queries (Common Table Expressions) to achieve the results like below

WITH t
AS (
    SELECT sum(clicks) c
    FROM TABLE
    WHERE event_date >= '1999-01-01'
    GROUP BY keyword_id
    )
SELECT c
FROM t
WHERE c > 10