Newbie help - UNION operator

harofreak00 · #1 (**permalink**) 04-27-10, 18:42

Hey guys, working on a simple query here, but I'm not getting the results I expect. Here is the exact question I am to work:

Quote:

Find the book code and book title for each book whose price is more than $10 or that was published in Boston.

Here is what I came up with:

Code:

SELECT B.BookCode, B.Title
FROM Book B
WHERE B.Price > '10'
UNION
SELECT B.BookCode, B.Title
FROM Book B, Publisher P
WHERE B.PublisherCode = P.PublisherCode;

However, this returns all the Books, even though I shouldn't. What did I do wrong? The chapter I am studying is specifically going over the SET operators (UNION, INTERSECT & MINUS), and the ANY and ALL operators. I figured UNION was closest to the example in the book, so thats why I choose that.

r937 · #2 (**permalink**) 04-27-10, 19:01

your UNION approach was very good, but it was incomplete

in the second of the SELECTs, you did nothing to restrict the rows to those books published in boston

harofreak00 · #3 (**permalink**) 04-27-10, 19:05

whoa, whoops.

Round 2:

Code:

SELECT B.BookCode, B.Title, price
FROM Book B
WHERE B.Price > '10'
UNION
SELECT B.BookCode, B.Title, price
FROM Book B, Publisher P
WHERE P.City = 'Boston'
AND B.PublisherCode = P.PublisherCode;

However, this code only displays books with prices higher than 10, it doesn't include the Boston books.

r937 · #4 (**permalink**) 04-27-10, 19:11

Quote:

Originally Posted by harofreak00

... it doesn't include the Boston books.

oh yes it does

harofreak00 · #5 (**permalink**) 04-27-10, 19:23

I guess its kind of a stupid question, because after further looking, ALL of the Boston books (only 2 of them), are both more then $10. I guess I have found the solution! Thanks for the help.

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