Re: Let-bindings in SQL statements

-----Original Message-----
From: pgsql-general-owner@postgresql.org
[mailto:pgsql-general-owner@postgresql.org] On Behalf Of Jon Smark
Sent: Thursday, January 26, 2012 9:38 AM
To: pgsql-general@postgresql.org
Subject: [GENERAL] Let-bindings in SQL statements

Hi,

Is it possible to do the equivalent of let-bindings in a pure SQL function?
I have a SELECT that invokes "now" multiple times.  It would be nicer to do
it only once and reuse the value.  Something like this:

LET right_now = SELECT now () IN
SELECT * FROM my_table WHERE right_now >= start AND ...

In PL/pgSQL this is easy, but I wonder about SQL...

Thanks in advance!
Jon

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No, not really.  In some cases you can use a CTE (WITH) clause to create a
single row with whatever names and values you need and then, using
Sub-Selects or CROSS JOIN, introduce that row into the appropriate parts of
the query.

 David J.