mysql - ネストされたクエリは、2 つのテーブルから 2 つの列を表示します

Question

テーブル

お客様

custno  |Custname
1       |Melinda
2       |Micheal
4       |Andrew

フライト

FlightNo | Day      | Destination | Cost
AF394    |monday    |Cape Town    |2700
FL2X     |Tuesday   |Paris        |5000
HK101    |Sunday    |hong kong    |3500

ご予約 フライト番号 |費用

1       | AF394    |2700
1       |FL2X      |5000
1       |HK101     |3500
2       |HK101     |3500
6       |AF394     |2700
7       |AF394     |2700

質問ディスプレイの予約の詳細は、メリンダという名前の顧客のCUSTNO,FKIGHTNO,DESTINATINとで構成されています。DAY

初心者ですMySQL、誰かが私が質問を解決するのを手伝ってくれることを願っています!!

Answer 1

SELECT Customer.custno, Reservation.Flightno, Flight.Destination, Flight.Day
FROM Flight LEFT OUTER JOIN Reservation ON Flight.FlightNo = Reservation.Flightno RIGHT OUTER JOIN Customer ON Reservation.Custno = Customer.custno WHERE (Customer.Custname = 'Melinda')

結果セット

1   AF394   Cape Town   monday
1   FL2X    Paris           Tuesday
1   HK101   hong kong   Sunday

Answer 2

--with joins
select r1.custno,r1.flightno,f1.destination,f1.day
from customer c1 join reservation r1 on c1.custno = r1.custno
                 join flight f1 on r1.flightno = f1.flightno
where c1.custname = 'Melinda'

--with nested queries
select (select custno from customer where custname = 'Melinda') custno,
        f1.flightno,f1.destination,f1.day
from flight f1 
where exists (
               select 1 
               from reservation 
               where flightno = f1.flightno and 
                     custno = (
                                select custno
                                from customer 
                                where custname = 'Melinda'
                               )
              )

Answer 3

select
(select custno from customer where custname='Melinda'), 
custno, 
flightno, 
day, 
destination 

from flight 
where flightno in (select flightno 
                   from reservation 
                   where custno in (select from where custname='Melinda'))