Question

I’m trying to select multiple rows over different tables but I can’t get it to work whatever I do.
I get this error:

Error(14,1): PL/SQL: ORA-00918: column ambiguously defined

Code (Note, this is part of a trigger, that’s why there’s the :new):

SELECT brw.borage, bt.agelower, bt.ageupper
INTO borAge, minAge, maxAge
FROM Borrower brw, BookTitle bt
  INNER JOIN BookCopy bc ON  :new.bcID = bc.bcID
  INNER JOIN BookTitle bt ON bt.isbn = bc.isbn

NOTE: BookTitle has only ONE ageLower and ageUpper column. There’s no declerations apart from borAge, minAge and maxAge either.

Answer 1

Tre problem is that you have two times the sames alias, try this:

SELECT brw.borage, bt.agelower, bt.ageupper
INTO borAge, minAge, maxAge
FROM Borrower brw, BookTitle bt
  INNER JOIN BookCopy bc ON  :new.bcID = bc.bcID
  INNER JOIN BookTitle bt2 ON bt2.isbn = bc.isbn

but this can give you more results then expected, because you put BookTitle table on the FROM part.

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I think that only this might be what you really need:

SELECT brw.borage, bt.agelower, bt.ageupper
INTO borAge, minAge, maxAge
FROM Borrower brw
  INNER JOIN BookCopy bc ON  :new.bcID = bc.bcID
  INNER JOIN BookTitle bt ON bt.isbn = bc.isbn