Re: joining tables

Let me step back a bit, as I realize upon further reflection that the first method will not work.

As far as the issue about two “Ted” records, read it as though I said two “Ted D” records. It refers to two records in the same table with the same key value. If “Ted D” appeared twice in table 1 and twice in table 2, the join would give four resulting records (all combinations of the records from table 1 and the records from table 2 (and the records from table 3) — that’s fundamentally how a join works. If you don’t want that, then make sure that there are no duplicates within each of the tables.

> On Sep 3, 2019, at 9:35 AM, TedJones <ted(at)mentra(dot)co(dot)uk> wrote:
>
> Hi Jack
>
> I'm not sure if I understand your comment about two 'Ted' fields and
> duplication of rows. In the example below there is 'Ted' twice in Table3 1
> and 3 and must appear twice as I've shown in the result as the data in the
> rest of the row is different. I agree with no duplication of rows if all of
> the row is the same.
>
> Ted
>
> Table: 1
> Author Title Sales Publication Date
> Jim A aa I
> Ted B bb J
> Dave C cc K
> Ted D dd L
>
> Table: 2
> Author Publisher
> Jim him
> Ted me
> Dave me
> Will you
> Gary him
>
> Table:3
> Author Title Country
> Ted B UK
> Ted D US
> Jim A UK
> Dave C UK
>
> Combined table: Result
> Author Title Publication Date Publisher Sales Country
> Ted B J me bb UK
> Ted D L me dd US
> Jim A I him aa UK
> Dave C K me cc UK
> Gary null null him null null
> Will null null you null null
>
>
>
>
> --
> Sent from: https://www.postgresql-archive.org/PostgreSQL-pgadmin-support-f2191615.html
>
>