エラーのための関係代数チェック

Question

こんにちは、私の仕事を確認してください。私がこのことを正しく行っていて、どんな助けにも大いに感謝しているかどうかはわかりません。私は蝶ネクタイの使用を許可していません。ありがとうございました。

質問：

Books (ISBN, Title, Authors, Publisher, Ed, Year, Genre) 
Patron (MemberNumber, FirstName, LastName, AddressLn1, AddressLn2, City, State, Zipcode) 
Loan (MemberNumber,ISBN,DateLoaned,DateDue, DateReturned) 

Business Logic 
• You may assume that the library only has one copy of each book. 
• Each book may have many authors. If a particular book has multiple authors, they are listed as a comma separated string. You may assume that the same author always uses the same exact name and no two authors will have the same name. 
• Year is stored as an integer. 
• DateLoaned, DateDue, and DateReturned are stored as a date. 
• When a book is initially lent out, DateReturned is set to be NULL, upon its return, the value is updated. 

1.1. Find all books that were loaned out after 12/22/2012. Show the ISBN, Title, and DateDue. 
1.2. Find all library patrons who have borrowed a book titled "Database Systems". Show their FirstName, LastName, and DateLoaned. 
1.3. Find all books that were ever loaned out. Display the ISBN. 
1.4. Find all books returned before 12/22/2012. Display the ISBN. 
1.5. Find all books returned on or after 12/22/2012. Display the ISBN. 
1.6. Find all books returned either (before 12/22/2012) or (on or after 12/22/2012) Display the ISBN. 
1.7. In 1 sentence explain the difference between 1.3 and 1.6. 
1.8. Find all patrons who have never borrowed a book. 
1.9. Find all books with Genre "Mystery" that have NEVER been loaned out. 
1.10. Create a new attribute ImportantDates. A date is important if it is in the Loan relation either as a DateLoaned or a DateDue. Display ImportantDates. 
1.11. Find all library patrons who have borrowed a book with an author "James Stewart". You may use the expression LIKE "%James Stewart%" in your Relational Algebra. 
1.12. Find all library patrons who have never borrowed a book with an author "James Stewart". You may use the expression LIKE "%James Stewart%" in your Relational Algebra. 
1.13. Find all library patrons who have only borrowed a book with an author "James Stewart". If they have ever borrowed a book without the author "James Stewart" they should be excluded. You may use the expression LIKE "%James Stewart%" in your Relational Algebra.  

回答：私はどのようにあるか見当もつかないよう

1.1) πISBN,TITLE,DATEDUE(σDATELOANED > 12222012 AND BOOKS.ISBN = LOAN.ISBN(LOAN X BOOKS) 
1.2) πFIRSTNAME,LASTNAME,DATELOANED(σTITLE = "DATABASE SYSTEMS" AND BOOKS.ISBN = LOAN.ISBN AND PATRON.MEMBERNUMBER = LOAN.MEMBERNUMBER(BOOKS X PATRON X LOAN)) 
1.3) πISBN(σDATELOANED <> "NULL" AND BOOK.ISBN = LOAN.ISBN(LOAN X BOOKS)) 
1.4) πISBN(σDATELOANED < 12222012 AND BOOK.ISBN = LOAN.ISBN(LOAN X BOOKS)) 
1.5) πISBN(σDATELOANED >= 12222012 AND BOOK.ISBN = LOAN.ISBN(LOAN X BOOKS)) 
1.6) πISBN(σDATELOANED >= 12222012 OR DATELOANED <12222012 AND BOOK.ISBN = LOAN.ISBN(LOAN X BOOKS)) 
1.7) 1.3 AND 1.6 are the same as they both find books that have been loaned. 
1.8) σDATELOANED = "NULL" AND PATRON.MEMBERNUMBER = LOAN.MEMBERNUMBER(LOAN X PATRON) 
1.9) σGENRE = "MYSTERY" AND BOOKS.ISBN = LOAN.ISBN AND DATELOANED = "NULL" 
1.10) LOAN(DATELOANED,DATEDUE) -> IMPORTANTDATE 

あなたが私に1.11、1.12、または1.13のいずれかの例を与えてもらえLIKE式を使用する。それは私が関係代数を使用しなければならなかったので、約一年となっている

You may use the expression LIKE "%James Stewart%" in your Relational Algebra. 

が、それはあなたの前の条件は、これがある（あるものは何でも次のようになります。

Answer 1

教授はそれを行う方法をあなたに言いました行が続くあなたのための作業）：

LIKE %James Stewart% 

SQLステートメントは、次のようになります

Select * from patrons p where Books.author LIKE %James Stewart% 

あなたの研究では、関係代数はSQLの関数を扱わないことが分かります.SQLの関数は純粋に数学的なものだけを見ています。