Solved

Database table structure

Posted on 2013-05-20
3
310 Views
Last Modified: 2013-05-20
One table "COMPANIES" needs to be linked to another table "CONTACTS".  Here is the twist: the contact for each company will change over time, but we need to keep the contacts.  My initial solution was to create a join table named something like "ACTIVE_CONTACT" that would hold pairs of the Company ID and the Contact ID, but i didn't know how to prevent a duplicate Company ID from being entered in the "ACTIVE_CONTACT" table. How would I do that?

Or, maybe using a join table is not the way to go?
0
Comment
Question by:rrhandle8
[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
3 Comments
 
LVL 29

Accepted Solution

by:
Paul Jackson earned 500 total points
ID: 39182896
A join table is the way to go. If you need to keep previous company contacts I would have a join table as you have described but rather than calling it active_contact just call it company_contacts and as well as the Company Id and Contact Id have another column called Active and make it a bit datatype which would be set for active contact records. You would make the Primary Key of this table a joint key of the Company Id and the Contact Id
Doing it this way means you would have a history of company contacts and the active contacts.

Alternatively if you felt that there was no need to keep a history of the contacts for each company in the company_contacts table you would just use Columns of Company ID and Contact ID and make them a company id the primary key for the join table to prevent duplicate contacts for a company. Obviously you will need logic in your stored procedures or business logic to delete a current active contact for a company when another is added.
0
 

Author Comment

by:rrhandle8
ID: 39182989
I've requested that this question be deleted for the following reason:

I decide to make the Company ID column unique.  
0
 

Author Closing Comment

by:rrhandle8
ID: 39182990
Jacko72,  I did not see your answer when I tried to delete the question.  I am awarding you now.  Thank you.
0

Featured Post

SharePoint Admin?

Enable Your Employees To Focus On The Core With Intuitive Onscreen Guidance That is With You At The Moment of Need.

Question has a verified solution.

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

Everyone has problem when going to load data into Data warehouse (EDW). They all need to confirm that data quality is good but they don't no how to proceed. Microsoft has provided new task within SSIS 2008 called "Data Profiler Task". It solve th…
JSON is being used more and more, besides XML, and you surely wanted to parse the data out into SQL instead of doing it in some Javascript. The below function in SQL Server can do the job for you, returning a quick table with the parsed data.
This video shows, step by step, how to configure Oracle Heterogeneous Services via the Generic Gateway Agent in order to make a connection from an Oracle session and access a remote SQL Server database table.
Viewers will learn how to use the SELECT statement in SQL and will be exposed to the many uses the SELECT statement has.

734 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