Re: Can someone check this ER design please

From: Vicente Barreiro <vbarreiro_at_mediaone.net>
Date: Fri, 09 Mar 2001 02:31:03 GMT
Message-ID: <HfXp6.295$nr.19620@typhoon.mn.mediaone.net>

I think that you could model this with only two tables:

Owner                  |       -0---------------*-<    | Transfer
      OwnerID(PK) |                                          |       OwnerID
asGiver(FK)  (Part of the PK)
                             |        -0--------------*--<   |

OwnerID as Getter(FK) (Part of the PK)

In words:
* For each Owner we can remember its Id
* For each Transfer we can remember who is the giver (an Owner), and who is a getter (an Owner)
* A transfer is a group of records in the Transfer table and the primary key is the combination of Giver/Getter
* For each Owner there can be none or many owners to wich he transfer * For each Owner there can be none or many owners from which he received a transfer.
* For each Transfer we could add more info like pctg of share or credit or date, etc.

Let's see some instances:

Owner

---

Uncle Rich
AuntMoney
BrotherPoor

Transfer

---

Giver                Getter
---------          ----------
UncleRich        BrotherPoor
UncleRich        AuntMoney

BrotherPoor AuntMoney

Hope this helps.

Vicho.

Simon Kearns <skearns_at_iconz.co.nz> wrote in message news:3aa81fd7_at_news.nz.asiaonline.net...
> I am building a DB for recording Land Shareholding Transfers.
> Shares are transferred when someone dies to their relatives. i.e. split
> amongst one or more beneficiaries
> My design works but I'm not confident that it is completely correct.
> 1. The big issue that concerns/confuses me is that:
> "Owners transfer shares to other Owners"
> i.e. therefore, an Owner is at different times both a Sharegiver and a
> Sharegetter.
> I solve this problem by a JOIN on tblOwner as tblSharegetter
> 2. The other issue is questions of whether the DB tables have associative
 or
> attributive qualities ( and whether it matters all that much!)
>
> Here's the cutdown ERD
>
> tblOwner
> |OwnerID(pk)|
>
> has one to many relationship with
> (one owner may be a sharegiver in zero or more TransferEvents)
>
> tblTransferEvent
> |EventID(pk)|OwnerID(fk)|
>
> has one to many relationship with
> (one TransferEvent may include zero or more TransferCredits)
>
> tblTransferCredit
> |CreditId(pk)|EventID(fk)|OwnerID as SharegetterID(fk)| --it's this part
> which i'm unsure about!!
>
> Thanks
> Simon
>
>
>
Received on Thu Mar 08 2001 - 20:31:03 CST