Want to protect your cyber security and still get fast solutions? Ask a secure question today.Go Premium

x
?
Solved

Can a PK be an FK as well ?

Posted on 2007-11-15
3
Medium Priority
?
1,130 Views
Last Modified: 2008-03-23
Hello,

Can a PK be an FK as well ?

Thank you.
0
Comment
Question by:matthew016
3 Comments
 
LVL 20

Assisted Solution

by:steelseth12
steelseth12 earned 800 total points
ID: 20292600
foreign key of one table is the primary key of another table.
For the field to be the primary key of table A and the foreign key of table B ... No. Foreign key needs to take the values from table B.
0
 
LVL 1

Accepted Solution

by:
kiwi_nz earned 1200 total points
ID: 20295410
yes a pk can be an fk - however this must be done in a special way. The trick is you must have two foreign keys that then composite into a Primary key - this is useful for when tables would otherwise have a many to many relationship you can put an intermediary table in between them and use the PK from each primary table as an FK in the intermediary table thereby creating a one to many - int table - many to one relationship.

Personally I dislike this method and always give the intemediary table a primary key and then add the two FK's thus making sure every single record in every single table is unique
0
 
LVL 9

Author Comment

by:matthew016
ID: 21189650
The answer was just yes, no special way needed
0

Featured Post

Free Backup Tool for VMware and Hyper-V

Restore full virtual machine or individual guest files from 19 common file systems directly from the backup file. Schedule VM backups with PowerShell scripts. Set desired time, lean back and let the script to notify you via email upon completion.  

Question has a verified solution.

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

Introduction This article is intended for those who are new to PHP error handling (https://www.experts-exchange.com/articles/11769/And-by-the-way-I-am-New-to-PHP.html).  It addresses one of the most common problems that plague beginning PHP develop…
In this blog post, we’ll look at how using thread_statistics can cause high memory usage.
In this Micro Tutorial viewers will learn the basic shortcuts and functions of Illustrator. The viewer will learn about the paintbrush tool, anchor points, font sizing, and more.
In this second Micro Tutorial in the series,  viewers will learn more basic shortcuts and functions of Illustrator. In this tutorial you will learn about the eyedropper tool, zoom , ellipses and more.
Suggested Courses
Course of the Month14 days, 17 hours left to enroll

577 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