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From: Gareth Evans <[email protected]>
To: JORGE MALDONADO <[email protected]>
Cc: [email protected]
Subject: Re: A situation with one parent table and 3 child tables
Date: Mon, 2 Oct 2023 22:46:00 +0100
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAAY=A7_wHBKkKFxuxXc7A+fr3TYGmWS9-hCGghLRDcQAAa_wfQ@mail.gmail.com>
References: <CAAY=A7_wHBKkKFxuxXc7A+fr3TYGmWS9-hCGghLRDcQAAa_wfQ@mail.gmail.com>

Hi Jorge,

Several 1:m relationships may be appropriate where the number of corresponding records on the m side can be 0, 1 or more.

If the child entities vary little or not at all in structure, but represent different “types”, a single 1:m might suffice with “type” as an attribute at the many end, and suitable indexes, and filtering at the application level.

It's difficult to generalise.  If you can give more information on the scenario, better advice may be forthcoming.

Kind regards,
Gareth


> On 2 Oct 2023, at 21:59, JORGE MALDONADO <[email protected]> wrote:
> 
> 
> Hi,
> 
> I have one parent table (table_p) with 3 child tables (table_ch1, table_ch2 and table_ch3). Each record of the parent table can be associated with 1 and only 1 child table records. This means that:
> 
> * Some records of the table_p will link to records of table_ch1
> * Some records of the table_p will link to records of table_ch2
> * Some records of the table_p will link to records of table_ch3
> 
> At first look, this does not make very much sense to me. I thought about considering 3 parent tables, one for each child table. However, the 3 parent tables would have the same exact structure and I would like to know if there is a workaround for this issue.
> 
> Thanks in advance.
> 
> Jorge Maldonado

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