Hi
I am trying to create inbox table in which entries may came from multiple tables. For example in my inbox entries may be received memos and and received circulars.
How can i have multiple foreign keys to the inbox table. One option may be to add foreign key for each parent table. I want to make design flexible so that if in future if i want to join more tables with this inbox table it can be done easily.
I read somewhere about composite foreign keys does they apply here?

You can add as many foreign keys as the design requires, and if the design requires it you can have composite foreign keys too.

There is not enough information to give you answers specific to your situation.

pootle flump ur codings are working excelent.

Thanks for the reply. could you please define composite foreign key for me and when it is used.
is there any way to workaround multiple foreign keys.
In my case Memo tables are as follows
==========
MemoMaster
==========
MemoID PK
ThroughEmpID FK
MemoDate
Subject
MemoText
==========
MemoDetail
==========
MemoDetailID PK
MemoID FK
EmployeeID FK
AckDate

Almost similar structure is for Circular

Can you suggest the possible inbox table structure

A composite foreign key is used in all but the most trivial databases that use natural keys for the primary keys.
I don't know if you are using surrogate keys or not, but looking at what you have posted it seems likely, in which case you would not use composite foreign keys.

NOTE that "multiple foreign keys" and "composite foreign keys" are not the same thing.

It seems to me you could do with stopping now and reading up relational database design and concepts. This is the best whistle stop tour of the subject I know of:
The Relational Data Model, Normalisation and effective Database Design

pootle flump ur codings are working excelent.

sounds like you want some for of sub/super types

top level table identifies a type of message/communication
and stores all relevent data common to all forms of communication
then for each type you hav a sub table which stores datat relevent to just that communication

so that could be
table: inbox
id
communicationtype
timeofevent

emailtable
inboxID
emailfrom
emailcontents

memo
ID
inboxid
URLtoDocument

telecon
ID
inboxid
whowith
notesofconversation

suggest you google sub/super types

Thanks for your reply i will get back to u soon after studying as u suggested