Referential integrity b/w Parent and child tables of DB2

vikas kumar jain · New User Joined: 02 Aug 2006 Posts: 9 Location: noida

I want to know whether to set the referential integrity b/w Parent and child tables of DB2, is it must that we need the referential table( Child table) empty(with no data)?

wanderer · Posted: Fri Jun 22, 2007 10:58 am

I don't remember it exactly right now, but no, it need not be empty. Although the table will go to CHECK PENDING status and you will have to run a CHECK DATA utility.

vikas kumar jain · New User Joined: 02 Aug 2006 Posts: 9 Location: noida

Thanks a lot....
Cud u tell that what is basically CHECK DATA utility and what it does in brief?

wanderer · Posted: Fri Jun 22, 2007 1:40 pm

It checks the table data for violation of constraints. Foreign key is one of the constraints. If there are no violations then CHECK PENDING status is removed.

This is DB2's way of cautioning the user about integrity of data.

Please see the 'Utility Gude' listed under link "Manual" on top of this page for more details. Hope it helps.

prasadvrk · Posted: Fri Jun 22, 2007 2:57 pm

A foreign key could be null, but if present should be the primary key in the parent table.

eg. An employee need not be associated with a department in EMP table but if an employee has department say 01 then there should be a row with 01 as department number in DEPT table

sagard · New User Joined: 16 May 2007 Posts: 4 Location: Pune

I am not sure i understand your last quote,
'A foreign key could be null, but if present should be the primary key in the parent table.'
for what i understand is that foreign key for one table is primary key for some other table & primary key cannot be null.

tosaurabh20 · New User Joined: 08 Jun 2007 Posts: 26 Location: Noida

vini_srcna · Posted: Thu Jun 28, 2007 4:59 pm

That makes more sense provided the foreign key is defined as nullable field. So i would say it is not a standard solution and you need to have a look at the catalog before deciding it.