Finding records in main table that match records in another table in SQL Server

Question

I have a SQL Server database with three tables: Trips , Slices , and Legs .

Each Trip has a one to many relationship with Slices and Slices has a one to many relationship with Legs .

Trips represents a full trip, a slice represents only the outbound or return portions of a trip, and the legs represent all the stops in either outbound or return slices.

I want to be able to find all the trips with matching legs.

Here's look at the tables:

Trips :

tripId  saleTotal   queryDate
1       $200            6/10/2015
2       $198            6/11/2015

Slices :

sliceId     connections duration    tripIdFK
1           1           50          1 
2           1           45          1 
3           0           60          2 
4           1           85          2 

Legs :

legId   carrier flightNumber    departureAirport    departureDate   ArrivalAirport  ArrivalDate sliceIDFK
1       AA      1               JFK                 7/1/2015        LON             7/2/2015    1 
2       AA      2               LON                 7/2/2015        FRA             7/2/2015    1 
3       AA      11              FRA                 7/10/2015       LON             7/10/2015   2
4       AA      12              LON                 7/10/2015       JFK             7/10/2015   2 

5       UA      5               EWR                 8/1/2015        LAX             8/1/2015    3
6       UA      6               LAX                 8/5/2015        ORD             8/5/2015    4 
7       UA      7               ORD                 8/5/2015        EWR             8/5/2015    4

How would I be able to find all the trips where the all the carrier and flight numbers match such as in legId 1-4 by searching departureAirport/arrivalAirport (JFK/FRA)?

In other words, legId 1-4 is one unit with the details for Trip 1 and legId 5-7 is another unit with the details for Trip 2. I need to find which other trips match exactly legId 1-4 details (except for PK and FK), etc. Any help would be greatly appreciated!!

Answer 1

Hope this helps.

Just pass the base TripId (in @BaseTripID) with which you want to compare other records. I assume that you are concerned only about carrier,flightNumber,departureAirport,ArrivalAirport to match exactly with any other trip regardless of date fields.

create table Trips(tripId int,saleTotal int,queryDate date)
create table Slices(sliceId int ,connections int,duration int ,tripIdFK int)
create table Legs(legId int, carrier char(2), flightNumber int, departureAirport char(3), departureDate date, ArrivalAirport char(3), ArrivalDate date, sliceIDFK int)


insert into Trips values(1,200,'6/10/2015'),(2,198,'6/11/2015'),(3,300,'6/15/2015'),(4,200,'6/21/2015')
insert into Slices values(1,1,50,1),(2,1,45,1),(3,0,60,2),(4,1,85,2),(5,1,50,3),(6,1,45,3),(7,1,45,4),(8,1,45,4)
insert into Legs values(1,'AA',1,'JFK','7/1/2015','LON','7/2/2015',1) ,
(2,'AA',2,'LON','7/2/2015','FRA','7/2/2015',1),
(3,'AA',11,'FRA','7/10/2015','LON','7/10/2015',2),
(4,'AA',12,'LON','7/10/2015','JFK','7/10/2015',2),
(5,'UA',5,'EWR','8/1/2015','LAX','8/1/2015',3),
(6,'UA',6,'LAX','8/5/2015','ORD','8/5/2015',4),
(7,'UA',7,'ORD','8/5/2015','EWR','8/5/2015',4),
(8,'AA',1,'JFK','7/11/2015','LON','7/12/2015',5),
(9,'AA',2,'LON','7/12/2015','FRA','7/12/2015',5),
(10,'AA',11,'FRA','7/20/2015','LON','7/20/2015',6),
(11,'AA',12,'LON','7/20/2015','JFK','7/20/2015',6),
(12,'AA',1,'JFK','7/1/2015','LON','7/2/2015',7) ,
(13,'AA',2,'LON','7/2/2015','FRA','7/2/2015',7),
(14,'AA',11,'FRA','7/10/2015','BEL','7/10/2015',8),
(15,'AA',12,'BEL','7/10/2015','JFK','7/10/2015',8)

--select * from  Trips
--select * from  Slices
--select * from  Legs

-------------------------------------------------------------------

Declare @BaseTripID int = 1, @Legs int ,@MatchingTripID int

declare @BaseTrip table(carrier char(2), flightNumber int, departureAirport char(3), ArrivalAirport char(3),row_no int)
declare @MatchingTrip table(carrier char(2), flightNumber int, departureAirport char(3), ArrivalAirport char(3),row_no int,legid int,tripid int)


insert into @BaseTrip
select carrier, flightNumber, departureAirport, ArrivalAirport,ROW_NUMBER() over(order by l.legId) 
from Legs l join slices s on s.sliceId = l.sliceIDFK
where s.tripIdFK = @BaseTripID


select @Legs=count(*) from @BaseTrip


Insert into @MatchingTrip
select carrier, flightNumber, departureAirport, ArrivalAirport,ROW_NUMBER() over(partition by s.tripIdFK order by l.legId) as row_no,l.legId,s.tripIdFK
from Legs l join slices s on s.sliceId = l.sliceIDFK
and s.tripIdFK in 
(select s.tripIdFK
from Legs l join slices s on s.sliceId = l.sliceIDFK
and s.tripIdFK <> @BaseTripID
Group by s.tripIdFK having count(l.legId)=@Legs)


select @MatchingTripID = m.tripid
from @MatchingTrip m join @BaseTrip b 
on m.carrier = b.carrier
and m.flightNumber = b.flightNumber
and m.departureAirport = b.departureAirport
and m.ArrivalAirport = b.ArrivalAirport
and m.row_no = b.row_no
GROUP BY m.tripid HAVING COUNT(*) = @Legs


select s.tripIdFK as matchingTripID,l.legid,l.carrier,l.flightNumber,l.departureAirport,l.ArrivalAirport  
from Legs l 
join Slices s on s.sliceId = l.sliceIDFK
where s.tripIdFK = @MatchingTripID


---------------------
drop table Trips
drop table Slices
drop table Legs

making use of leg count is the key.Thus we are eliminating any matches other than completely identical legs(trip 4 with just two matching legs). So Now we get only Trip 3 as matching records.

please note that we are also excluding trips, that has any additional legs besides the matching ones. I hope this is what you expect, pair of Perfectly identical trips.

Answer 2

Ow, my brain hurts...

Replace all of the question marks (3 of them) with the trip ID of the trip where you want to check for similar trips.

select distinct s.tripIDFK as tripId
from Legs l
left join Slices s on l.sliceIDFK = s.sliceId
where s.tripIDFK != ?
and not exists (
  select carrier, flightNumber, departureAirport, departureDate
  from Legs l2
  left join Slices s2 on l2.sliceIDFK = s2.sliceId
  where s2.tripIDFK = s.tripIDFK
  except
  select carrier, flightNumber, departureAirport, departureDate
  from Legs l2
  left join Slices s2 on l2.sliceIDFK = s2.sliceId
  where s2.tripIDFK = ?
)
and not exists (
  select carrier, flightNumber, departureAirport, departureDate
  from Legs l2
  left join Slices s2 on l2.sliceIDFK = s2.sliceId
  where s2.tripIDFK = ?
  except
  select carrier, flightNumber, departureAirport, departureDate
  from Legs l2
  left join Slices s2 on l2.sliceIDFK = s2.sliceId
  where s2.tripIDFK = s.tripIDFK
)
order by s.tripIDFK

The meat of the query is the and not exists clauses. They get the leg data for one trip and effectively subtracts the leg data of another trip using the except clause. If you're left with nothing, then the second trip data contains all of the first trip data. You have to run the and not exists clause twice (with the operands reversed) to ensure that the two sets of trip data are truly identical, and that one is not merely a subset of the other.

This is in no way scalable to large numbers of rows.

Answer 3

Another approach is to determine/store a legsKey with each slice so you can find matching slices across trips.

For each slice, your legsKey is each leg's carrier and flight number appended, which you can do using For XML Path, like this

something like:

select
   distinct  
    stuff((
        select ',' + l.carrier + ':' + l.flightNumber
        from legs l
        where l.carrier = carrier and l.flightnumber = flightnumber
        order by l.carrier, l.flightnumber
        for xml path('')
    ),1,1,'') as legsList
from legs
group by carrier, flightnumber