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Databases

Marcia Haledjian
Marcia Haledjian
7,562 Points
Posted by Marcia Haledjian
Marcia Haledjian
7,562 Points

Database JOIN

Can anyone tells me if this is the correct statement?

-- Create a report that shows the title of the book, first and last name of the patron, email and all date fields of the loan.

SELECT books.title, patrons.first_name, patrons.last_name, patrons.email, loans.book_id, loans.patron_id, loans.loaned_on, loans.return_by, loans.returned_on from patrons INNER JOIN books, loans ON patrons.id = books.id;

3 Answers

Steven Parker
Steven Parker
231,248 Points
Steven Parker
Steven Parker
231,248 Points

:point_right: It looks like you have a few things to fix yet, here's some hints:

  • you seem to be selecting a few more things than the challenge asked for
  • your join seems to be trying to include too many tables at once
  • your join operation seems to be trying to match two unrelated fields

To get the most specific and accurate answers to your questions, be sure to always provide a link to the challenge itself.

Eszter Adam
Eszter Adam
9,175 Points
Eszter Adam
Eszter Adam
9,175 Points

What about this? SELECT first_name,last_name, email, title, book_id, patron_id, loaned_on, return_by, returned_on FROM loans INNER JOIN patrons ON loans.patron_id = patrons.id INNER JOIN books ON loans.book_id = books.id;

kw8
kw8
13,271 Points
kw8
kw8
13,271 Points

This is way late, but I just got to this problem and I figured it out! I did some searching online (https://javarevisited.blogspot.com/2012/11/how-to-join-three-tables-in-sql-query-mysql-sqlserver.html) found that in google searching "can you join 3 tables in SQL?"

Here is some of the text that helps put it in context:

"Three table JOIN syntax in SQL Here is a general SQL query syntax to join three or more tables :

SELECT t1.col, t3.col FROM table1 join table2 ON table1.primarykey = table2.foreignkey JOIN table3 ON table2.primarykey = table3.foreignkey;

"

So for this question I did:

"SELECT patrons.first_name, patrons.last_name, patrons.email, books.title, loans.loaned_on, loans.return_by, loans.returned_on FROM patrons JOIN loans ON patrons.id = loans.patron_id JOIN books ON loans.book_id=books.id; "

and it seems to provide a single table with the requested columns from the 3 different tables all in one. Notice the second JOIN clause is just tacked right on to the end of the first JOIN clause. I don't know if this is 100% correct structure, but the result seems to be exactly what the question is asking for: information about all books loaned out from all 3 tables. Hope this helps.