Re: Postgres views cannot use both union and join/where

On Tuesday, October 19, 2021, Michael Lewis <mlewis(at)entrata(dot)com> wrote:

> On Tue, Oct 19, 2021 at 3:48 PM Mithran Kulasekaran <
> mithranakulasekaran(at)gmail(dot)com> wrote:
>
>> create view template_view (id, name, description, is_staged) as
>> select t.id,t.name, t.description, false as is_staged
>> from template t
>> left join template_staging ts on t.name = ts.name and ts.name is null
>>
>>
> Does that work? I've only seen that type of logic written as-
>
> left join template_staging ts on t.name = ts.name
> where ts.name is null
>

The are functionally equivalent, though the timing of the expression
evaluation differs slightly.

It could also be written as an anti-join:

Select * from template as t where not exists (select 1 from
template_staging as ts where t.name = ts.name)

David J.