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help / color / mirror / Atom feedFrom: Shaozhong SHI <[email protected]>
To: Steve Midgley <[email protected]>
Cc: pgsql-sql <[email protected]>
Subject: Re: A function to find errors in groups in a table
Date: Fri, 10 Jun 2022 00:13:20 +0100
Message-ID: <CA+i5Jwb3q=dJ3LT0MmpFOhcxENuSkLV9Stv+fj5y6U=7HCgDCQ@mail.gmail.com> (raw)
In-Reply-To: <CAJexoSJ3g9W1XtdUVnss+5cw=r-ek-JSfiGUaBxCGG=BJLmHQQ@mail.gmail.com>
References: <CA+i5JwZ1y=KNn8uJr_DLe2LZCeLxVxY0osHBVoaELUVC=JWr6A@mail.gmail.com>
<CA+i5JwZCt0c1V-LexLo50Oa+r_UVLM26ZQ4pqq2d9XYaBebKjA@mail.gmail.com>
<CAJexoSJ3g9W1XtdUVnss+5cw=r-ek-JSfiGUaBxCGG=BJLmHQQ@mail.gmail.com>
The first two can be regarded right. Certainly, the last one must be
wrong. How can a primary flow get into a secondary flow?
That is odd.
Regards,
David
On Thursday, 9 June 2022, Steve Midgley <[email protected]> wrote:
>
>
> On Thu, Jun 9, 2022 at 6:37 AM Shaozhong SHI <[email protected]>
> wrote:
>
>> There is a table full of grouped values like the following
>>
>> nodeid link_type primary
>> 11 outflowlink 1
>> 11 inflowlink 1
>> 11 outflowlink 2
>>
>> Primary of 1 indicates a primary water course. Primary of 2 indicates a
>> secondary water course.
>>
>> Obviously, one of the out flow links is an error, as its primacy value is
>> 2. It is wrong that water flows from a primary water course into a
>> secondary water course.
>>
>> How can a function can be designed to find and report such errors?
>>
>
> Is the problem that there exists this row:
>
> 11 outflowlink 2
>
> But there is no corresponding row:
>
> 11 inflowlink 2
>
> So that you need to find all "orphan" rows that don't have a corresponding
> member with the opposing data field inflowlink or outflowlink where the
> "primary" column is the join field between the two rows?
>
> Thanks for clarifying your problem,
> Steve
>
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To: [email protected]
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Subject: Re: A function to find errors in groups in a table
In-Reply-To: <CA+i5Jwb3q=dJ3LT0MmpFOhcxENuSkLV9Stv+fj5y6U=7HCgDCQ@mail.gmail.com>
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