Why can't use with?

Question

PostgreSQL

There is this request:

with min as
  (
   select
   cast(extract(epoch from time) as integer)
   from records 
   where time >= '2016-01-01 06:36:12' 
   order by time asc 
   limit 1
 ), max as (
   select
   cast(extract(epoch from time) as integer)
   from records 
   where time <= '2016-02-01 06:36:12'
   order by time desc
   limit 1
 )

select (max.time - min.time) t1

Why is the following error coming up?

SQL Error [42P01]: ОШИБКА: таблица "max" отсутствует в предложении FROM
  Позиция: 333

Answer 1

1) Select queries have a mandatory from part.
2) Columns in tables are not named
Try this:

with min as
  (
   select
   cast(extract(epoch from time) as integer) as time
   from records 
   where time >= '2016-01-01 06:36:12' 
   order by time asc 
   limit 1
 ), max as (
   select
   cast(extract(epoch from time) as integer) as time
   from records 
   where time <= '2016-02-01 06:36:12'
   order by time desc
   limit 1
 )

select (max.time - min.time) t1
from min, max