sql - How to get second row in PostgreSQL? -

i have next table:

column_name data_type     pk    nullable inc_id      bigint        yes   no dt_cr       timestamp     no    no email       varchar(255)  no    yes 

email column not unique, should use group email.

question: how can table minimal date, next row after minimal date , email related dates?

i read first_value , nth_value functions, code listed below, seems doesn't work correct.

select j1.email, j2.first_date, j2.second_date  (     select email      orders      group email) j1 left outer join (     select email,          first_value(dt_cr) on (order dt_cr rows between unbounded preceding , unbounded following) first_date,          nth_value(dt_cr, 2) on (order dt_cr rows between unbounded preceding , unbounded following) second_date      orders) j2   on (j1.email=j2.email); 

any ideas?

--edited maybe can done rank() function..

this query uses with construction works similar sub-queries. investigate query explain before use in production because may slow on big tables:

with orders (     select            email         , first_value(dt_cr) on wnd1 min_date         , nth_value(dt_cr, 2) on wnd1 second_date      orders     window wnd1 ( partition email order email, dt_cr) ) select distinct *  orders second_date not null;