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Editorial Team
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Asked: 2026-06-01T06:09:03+00:00

I am going to try to use left outer join between Ticket and Membership.

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I am going to try to use left outer join between Ticket and Membership.
However, it does not display the foreign key of NULL values on Ticket. Could you give me some answer for this what’s wrong with this query?
Thanks.

FROM Ticket t, Production pro, Performance per, Price, Price_level, Booking, Customer, Customer_Concession ccons, Membership, Member_concession mcons
WHERE t.performanceid = per.performanceid AND
  t.PRODUCTIONID = Price.PRODUCTIONID AND
  t.levelId = Price.levelId AND
  Price.PRODUCTIONID = pro.PRODUCTIONID AND
  Price.levelId = Price_level.levelId AND
  Booking.bookingId (+) = t.bookingId AND
  Customer.customerId = Booking.customerId AND
  ccons.cConcessionId (+) = Customer.cConcessionId AND  
  Membership.membershipId (+) = t.membershipId AND
  Membership.mConcessionId = mcons.mConcessionId 
ORDER BY t.ticketId
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1 Answer

  1. Editorial Team

    One potential problem you have is these two conditions:

      Booking.bookingId (+) = t.bookingId AND
  Customer.customerId = Booking.customerId AND

    Since you’re doing an outer join to Booking, its columns will appear as NULL when no match is found; but then your doing a normal join to Customer, so those rows will be eliminated since NULL cannot be equal to anything. You may want to change the second line to an outer join as well.

    But, I don’t know if that’s your primary problem, since I don’t actually understand exactly what you’re asking. What do you mean by “NULL value of the foreign key”? You haven’t specified what your foreign keys are.

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