Insert Statement Returns ORA-01427 Error While Trying To Insert From Multiple Tables

Question

I have this table F_Flight which I am trying to insert into from 3 different tables. The first, fourth and fifth columns are from the same, and the second and third columns from different tables. When I execute the code, I get a "single-row subquery returns more than one row" error.

insert when 1 = 1 then into F_Flight (planeid, groupid, dateid, flightduration, kmsflown) values 
(planeid, (select b.groupid from BridgeTable b where exists (select p.p1id from pilotkeylookup p where b.pilotid = p.p1id)), 
(select dd.id from D_Date dd where exists (select p.launchtime from PilotKeyLookup p where dd."Date" = p.launchtime)),
flightduration, kmsflown) select * from PilotKeyLookup p;

Answer 1

Your subqueries get multiple rows back, which is what the error message says. There is no correlation between the various bits of data and subqueries you're trying to insert into a single row.

This can be done as a much simpler insert...select with joins, something like:

insert into f_flight (planeid, groupid, dateid, flightduration, kmsflown)
select pkl.planeid, bt.groupid, dd.id, pkl.flightduration, pkl.kmsflown
from pilotkeylookup pkl
join bridgetable bt on bt.pilotid = pkl.p1id
join d_date dd on dd."Date" = pkl.launchtime;

This joins the main PilotKeyLookup table to the other two on the keys you used in your subqueries.

Storing an ID value instead of an actual date is unusual, and if launchtime has a time component - which seems likely from the name - and your d_date entries are just dates (ie all with time at midnight) then you won't find matches; you might need to do:

join d_date dd on dd."Date" = trunc(pkl.launchtime);

It also seems like this could be a view, as you're storing duplicate data - everything in f_flight could, obviously, be found from the other tables.