Question

I’m trying to create a view with row numbers like so:

create or replace view daily_transactions as
select 
    generate_series(1, count(t)) as id,        
    t.ic,
    t.bio_id,
    t.wp,    
    date_trunc('day', t.transaction_time)::date transaction_date, 
    min(t.transaction_time)::time time_in, 
    w.start_time wp_start,    
    w.start_time - min(t.transaction_time)::time in_diff,    
    max(t.transaction_time)::time time_out,     
    w.end_time wp_end,    
    max(t.transaction_time)::time - w.end_time out_diff,     
    count(t) total_transactions,
    calc_att_status(date_trunc('day', t.transaction_time)::date,
                    min(t.transaction_time)::time,
                    max(t.transaction_time)::time,
                    w.start_time, w.end_time ) status        
from transactions t
left join wp w  on (t.wp = w.wp_name)
group by ic, bio_id, t.wp, date_trunc('day', transaction_time),
         w.start_time, w.end_time;

I ended up with duplicate rows. SELECT DISTINCT doesn’t work either. Any ideas?

Transaction Table:

create table transactions(
    id serial primary key,    
    ic text references users(ic),
    wp text references wp(wp_name),
    serial_no integer,    
    bio_id integer,
    node integer,
    finger integer,
    transaction_time timestamp,    
    transaction_type text,        
    transaction_status text        
 );

WP table:

create table wp(
    id serial unique,   
    wp_name text primary key,
    start_time time,
    end_time time,
    description text,
    status text    
);

View Output:

Answer 1

CREATE OR REPLACE VIEW daily_transactions as
SELECT row_number() OVER () AS id
     , t.ic
     , t.bio_id
     , t.wp 
     , t.transaction_time::date AS transaction_date
     , min(t.transaction_time)::time AS time_in
     , w.start_time AS wp_start
     , w.start_time - min(t.transaction_time)::time AS in_diff
     , max(t.transaction_time)::time AS time_out
     , w.end_time AS wp_end
     , max(t.transaction_time)::time - w.end_time AS out_diff
     , count(*) AS total_transactions
     , calc_att_status(t.transaction_time::date, min(t.transaction_time)::time
                     , max(t.transaction_time)::time
                     , w.start_time, w.end_time) AS status
FROM   transactions t
LEFT   JOIN wp w ON t.wp = w.wp_name
GROUP  BY t.ic, t.bio_id, t.wp, t.transaction_time::date
        , w.start_time, w.end_time;

Major points

• generate_series() is a plain (set-returning) function, applied after aggregate functions. It produces multiple rows, thereby multiplying all output rows.
  The window function row_number() is also applied after aggregate functions, but only generates a single number per row.

• date_trunc() is redundant in date_trunc('day', t.transaction_time)::date. t.transaction_time::date achieves the same, simpler & faster.

• Use count(*) instead of count(t). Same result here, but a bit faster.

Some other minor changes.