Groups > comp.databases.postgresql > #825

Re: lateral query with dynamic column value

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From	Dimitri Fontaine <dim@tapoueh.org>
Newsgroups	comp.databases.postgresql
Subject	Re: lateral query with dynamic column value
Date	Tue, 01 May 2018 09:50:35 +0200
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luca.bocchi8@gmail.com writes:
> I need an help with lateral subqueries: 
>
> is it possible to perform it with a dynamically generated column name? 

No it is not. SQL is a statically typed language, the SQL engine
(parser, executor) needs to fully determine the data type of the result
of the query before running it.

        column_name             
>     ------------------------------------
>      user_id
>      warehouse_resume_attribute_user_id
>      resume_attribute_000m1_2
>      resume_attribute_00032_13
>      resume_attribute_00052_13
>      resume_attribute_00053_13
>      resume_attribute_00057_4
>      resume_attribute_00058_7
>      resume_attribute_00059_6
>      resume_attribute_00061_3

This looks like an EAV data model, which is the worst possible choice on
earth in the relational world. Normalize your data model and then it's
going to be very easy (and efficient) to write your queries.

Regards,
-- 
Dimitri Fontaine
https://masteringpostgresql.com

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lateral query with dynamic column value luca.bocchi8@gmail.com - 2018-04-30 14:03 -0700
  Re: lateral query with dynamic column value Dimitri Fontaine <dim@tapoueh.org> - 2018-05-01 09:50 +0200

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