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From: Shaozhong SHI <shishaozhong@gmail.com>
Date: Thu, 9 Jun 2022 14:37:27 +0100
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 <CA+i5JwZCt0c1V-LexLo50Oa+r_UVLM26ZQ4pqq2d9XYaBebKjA@mail.gmail.com>
Subject: A function to find errors in groups in a table
To: pgsql-sql <pgsql-sql@lists.postgresql.org>
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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?

Regards,

David

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<div dir=3D"ltr"><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail=
_attr">There is a table full of grouped values like the following<br></div>=
<div dir=3D"ltr"><div dir=3D"ltr"><div><br></div><div>nodeid=C2=A0 =C2=A0 =
=C2=A0link_type=C2=A0 =C2=A0 =C2=A0 primary</div><div><div>11=C2=A0 =C2=A0 =
=C2=A0 =C2=A0 =C2=A0 =C2=A0outflowlink=C2=A0 =C2=A0 =C2=A0 =C2=A01</div><di=
v>11=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 inflowlink=C2=A0 =C2=
=A0 =C2=A0 1</div><div>11=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 o=
utflowlink=C2=A0 =C2=A0 =C2=A02</div></div><div><br></div><div>Primary of 1=
 indicates a primary water course.=C2=A0 Primary of 2 indicates a secondary=
 water course.</div><div><br></div><div>Obviously, one of the out flow link=
s is an error, as its primacy value is 2.=C2=A0 It is wrong that water flow=
s from a primary water course into a secondary water course.</div><div><br>=
</div><div>How can a function can be designed to find and report such error=
s?</div><div><br></div><div>Regards,</div><div><br></div><div>David</div></=
div></div>
</div></div>

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