Using an Alias column in the where clause in Postgresql

Question

I have a query like this:

SELECT
    jobs.*, 
    (
        CASE
            WHEN lead_informations.state IS NOT NULL THEN lead_informations.state
                   


        

Answer 1

I believe the common solution is to use an inner SELECT for the calculation (or CASE statement in this case) so that the result of the inner SELECT is available to the entire outer query by the time the execution gets to that query. Otherwise, the WHERE clause is evaluated first and knows nothing about the SELECT clause.