X-Received: by 10.236.209.134 with SMTP id s6mr307008yho.40.1392155381055; Tue, 11 Feb 2014 13:49:41 -0800 (PST) X-Received: by 10.140.50.34 with SMTP id r31mr222980qga.15.1392155381028; Tue, 11 Feb 2014 13:49:41 -0800 (PST) Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!usenet.blueworldhosting.com!feeder01.blueworldhosting.com!peer01.iad.highwinds-media.com!news.highwinds-media.com!feed-me.highwinds-media.com!f11no17697042qae.1!news-out.google.com!y18ni7903qap.1!nntp.google.com!f11no17697039qae.1!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail Newsgroups: comp.databases.ms-sqlserver Date: Tue, 11 Feb 2014 13:49:40 -0800 (PST) In-Reply-To: Complaints-To: groups-abuse@google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=94.196.204.191; posting-account=dELd-gkAAABehNzDMBP4sfQElk2tFztP NNTP-Posting-Host: 94.196.204.191 References: User-Agent: G2/1.0 MIME-Version: 1.0 Message-ID: Subject: Re: A question about relationship From: rja.carnegie@gmail.com Injection-Date: Tue, 11 Feb 2014 21:49:41 +0000 Content-Type: text/plain; charset=ISO-8859-1 X-Received-Bytes: 2974 X-Received-Body-CRC: 2703822733 Xref: csiph.com comp.databases.ms-sqlserver:1679 On Tuesday, 11 February 2014 20:54:38 UTC, Erland Sommarskog wrote: > Tony Johansson (johansson.andersson@telia.com) writes: > > Yes a customer without order sounds ok > > But order without customer is incorrect. > > I would say that it depends on the business rules. :-) But, yes, it > would be a bit peculiar. > > In Northwind CustomerID is nullable, although there is no such order > in the data. Unfortunately, Northwind leaves a whole lot desired when it > comes to nullability, indexes etc. I don't remember if I ever worked in the Northwind database. (My actual training was some of the authentic courses for SQL Server 7.) So I don't know if some of its features are included intentionally to attract criticism for extra credit in class - you know, spot the little design mistakes. That can be good practice for real work. Or if it's just not particularly well done. It bothers me a little that most database courses I've seen are about developing yet another new customer and order database for a business, when that's the last thing that the world needs - unless you have an amazing new idea about how to do it. Maybe that's what they're looking for? But I suppose that (1) it's really about understanding how data table relationships work and how to use SQL to talk to your database, and (2) it's businessy. Whereas a course based around recording a kindergarten class's personal achievements, family relationships and friend and unfriendships, allergies, and favourite colours, TV shows, etc., for instance, might be too "out there". Although curiously, I run the database for - :-) Also... I /actually/ work in a room of around 30 men and, as far as I've noticed, 1 woman. That's not right. I should have my own office.