First, thanks every one for your patient and detailed answers. All your answers are very helpful. I really learn a lot from this.

We are not going to have many queries to the collection of all notes or note that shared between objects. We mainly associate each notes with each object.

So I think now I came to the two approaches by your posts:

1. create a noteTable for each parent Object. I heard this is proved preferred design.

The only thing is that I see all the columns are the same,(except the hearingID, or conferenceID column), so even this is repeatable for all the notes tables, still consider a good design?

NoteHearing: Noteid, notetype, createddate,hearingid,

NoteConference: Noteid, notetype, createddate,Conferenceid,

2. to create a Note table and a NoteBridge table.

Note: NoteID, NoteDetail, createDate, updateDate

NoteBridge: (or maybe call it NoteRelationship)

columns: NoteBridgeID(identitycolumn), Noteid, hearingId, conferenceid, interventionid.

The noteBridgeID+Noteid is the PK.

Am I correct? Thank you very much