How to apply several selects for several joins?

Question

I want to join columns from several tables. For one table join works fine

select org.catalog_truck.plate_number as "Госномер грузовика",
shift_id as "ID смены",
trip_id as "ID рейса",
*
from core.monitoring_stages
join org.catalog_truck
on vehicle_id = org.catalog_truck.catalog_truck_id
where gen_id = (SELECT max(gen_id)
FROM core.monitoring_tripmachine_generation
WHERE ready=true and timerange_from > '2024-09-23 00:00:00.000 +0300' and timerange_to < '2024-09-23 23:59:59.000 +0300')
ORDER by dtstart

But for two joins (and two selects in the first two lines I have an error)

select org.catalog_truck.plate_number as "Госномер грузовика",
select org.catalog_field.name as "Поле погрузки",   <--- select for the second join (error in this line)
shift_id as "ID смены",
trip_id as "ID рейса",
*
from core.monitoring_stages
join org.catalog_truck
on vehicle_id = org.catalog_truck.catalog_truck_id
where gen_id = (SELECT max(gen_id)
from core.monitoring_stages <--- second join
join org.catalog_field cf 
on field_id = org.catalog_field.name
FROM core.monitoring_tripmachine_generation
WHERE ready=true and timerange_from > '2024-09-23 00:00:00.000 +0300' and timerange_to < '2024-09-23 23:59:59.000 +0300')
ORDER by dtstart

Error text:

SQL Error [42601]: ERROR: syntax error at or near "select" Position: 66

Error position: line: 2 pos: 65

How to apply two selects for two joins?

Answer 1

You do not need to use multiple selects, once you've join two (or more) tables, you can select anything from the resulting table, like you already did with the monitoring_stages (if I didn't misunderstand your table schemas) :

select 
    org.catalog_truck.plate_number as "Госномер грузовика",
    org.catalog_field.name as "Поле погрузки",   -- Second join column
    shift_id as "ID смены",
    trip_id as "ID рейса",
    *
from 
    core.monitoring_stages
join 
    org.catalog_truck 
    on vehicle_id = org.catalog_truck.catalog_truck_id
join 
    org.catalog_field  -- Second table join
    on field_id = org.catalog_field.catalog_field_id
where 
    gen_id = (SELECT max(gen_id)
              FROM core.monitoring_tripmachine_generation
              WHERE ready = true 
              and timerange_from > '2024-09-23 00:00:00.000 +0300' 
              and timerange_to < '2024-09-23 23:59:59.000 +0300')
ORDER by dtstart;