Dina, I'm going to throw this "Teach Yourself SQL" book in the rubbish bin, and buy your book instead. You can explain how clever I already am in such concise terms.
What's the name of your book? Thanks for your help folks. Now I know where I have to go reading next. Cheers, Mike Kear Windsor, NSW, Australia AFP WebWorks -----Original Message----- From: Dina Hess [mailto:[EMAIL PROTECTED]] Sent: Sunday, 29 September 2002 2:35 AM To: SQL Subject: Re: Why External keys? > Actually there was no problem. I just saw the terms "primary key" and > "foreign key" and wasn't clear on what they meant. I have seen table > layouts where people have a table just containing keys and couldn't figure > out why. A primary key is just a unique identifer for a table record. A foreign key is the primary key of one table included as a field in another table to establish a relationship between the two tables. Sometimes it's necessary to create what's known as an intersection table if the relationship between two tables is many-to-many. That type of table could well include only the keys from the other two tables. > So you are saying that my query is actually an INNER JOIN?? That was the > next thing I had to come to grips with - Inner and outer joins. I've read > the part in the SQL book I have where it explains what inner and outer joins > are and its been double-dutch to me the first 5 times through. Yes, you are doing an inner join using Transact-SQL syntax. An inner join will only return records from the joined tables that have matching primary/foreign keys. An outer join will return *all* records from the starting table regardless of whether or not there are matching primary/foreign keys. ______________________________________________________________________ Signup for the Fusion Authority news alert and keep up with the latest news in ColdFusion and related topics. http://www.fusionauthority.com/signup.cfm Archives: http://www.mail-archive.com/[email protected]/ Unsubscribe: http://www.houseoffusion.com/index.cfm?sidebar=lists
