Please start any new threads on our new site at We've got lots of great SQL Server experts to answer whatever question you can come up with.

Our new SQL Server Forums are live! Come on over! We've restricted the ability to create new threads on these forums.

SQL Server Forums
Profile | Active Topics | Members | Search | Forum FAQ
Register Now and get your question answered!
Save Password
Forgot your Password?

 All Forums
 General SQL Server Forums
 Database Design and Application Architecture
 Can a column be a PK and FK and is that ok to do?
 Reply to Topic
 Printer Friendly
Author Previous Topic Topic Next Topic  

Constraint Violating Yak Guru

424 Posts

Posted - 10/19/2012 :  16:06:06  Show Profile  Visit Eagle_f90's Homepage  Reply with Quote
I have 2 tables (tblItems and tblNormalItems) which are a SuperType/SubType relationshipt (like a Person to Employe table). tblItems contains the common basic info of all items and tblNormalItems will contain only data unique to normal items. Is it ok for tblNormalItems to have a column called ItemID wich would be a PK for tblNormalItems but allso be a FK to tblItems (and can that be done by just two normal CONSTRANT calls)? Here is the code for tblItems:

CREATE TABLE dbo.tblItems
    ItemID bigint IDENTITY(0,1) NOT NULL,
    SectionID smallint NOT NULL,
    ItemName varchar(250) NOT NULL,
    ItemType smallint NOT NULL,
    ItemDescription varchar(MAX) NOT NULL,
    ItemImageID int NULL,
    CONSTRAINT FK_Items_SectionID FOREIGN KEY (SectionID) REFERENCES dbo.tblSectionInfo (SectionID),
    CONSTRAINT FK_Items_ItemType FOREIGN KEY (ItemType) REFERENCES dbo.tblItemTypes (ItemTypeID),
    CONSTRAINT FK_Items_ItemImageID FOREIGN KEY (ItemImageID) REFERENCES dbo.tblFiles (FileID)

If I get used to envying others...
Those things about my self I pride will slowly fade away.

Most Valuable Yak

15732 Posts

Posted - 10/19/2012 :  17:24:16  Show Profile  Visit robvolk's Homepage  Reply with Quote
Yes, that's perfectly fine and is the only way to guarantee a 1:1 cardinality between those tables.
Go to Top of Page
  Previous Topic Topic Next Topic  
 Reply to Topic
 Printer Friendly
Jump To:
SQL Server Forums © 2000-2009 SQLTeam Publishing, LLC Go To Top Of Page
This page was generated in 0.04 seconds. Powered By: Snitz Forums 2000