[2 days left] What’s wrong with your cloud strategy? Learn why multicloud solutions matter with Nimble Storage.Register Now

x
?
Solved

Foreign Key and Not Null

Posted on 2007-04-03
2
Medium Priority
?
195 Views
Last Modified: 2010-03-20
Hi

Just a basic question.  You can't have a foreign key on an item that is not null.  Is this correct?

Greg
0
Comment
Question by:greg_c
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
2 Comments
 
LVL 143

Accepted Solution

by:
Guy Hengel [angelIII / a3] earned 500 total points
ID: 18842173
?
no, that is not correct.

you can have a foreign key pointing from and pointing to a field that is not null.
however, you will need to have the referred value in the "master/lookup" table be present BEFORE you use that value in the child table.
0
 

Author Comment

by:greg_c
ID: 18842235
Thank you
0

Featured Post

Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

If you find yourself in this situation “I have used SELECT DISTINCT but I’m getting duplicates” then I'm sorry to say you are using the wrong SQL technique as it only does one thing which is: produces whole rows that are unique. If the results you a…
Occasionally there is a need to clean table columns, especially if you have inherited legacy data. There are obviously many ways to accomplish that, including elaborate UPDATE queries with anywhere from one to numerous REPLACE functions (even within…
In this video, Percona Director of Solution Engineering Jon Tobin discusses the function and features of Percona Server for MongoDB. How Percona can help Percona can help you determine if Percona Server for MongoDB is the right solution for …
Is your data getting by on basic protection measures? In today’s climate of debilitating malware and ransomware—like WannaCry—that may not be enough. You need to establish more than basics, like a recovery plan that protects both data and endpoints.…
Suggested Courses

656 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question