Assigning values to a range in Pgsql and inclusive / exclusive bounds

[Ron Clarke <rclarkeai@xxxxxxxxx>]

Hi, 

I've got a simple problem, but I'm convinced that there must be an elegant solution. I'm a refugee from the world of MSSQL, so I'm still finding some aspects of PostgreSQL alien. 

I'm trying to use the tstzrange datatype. My issue is correctly setting the bound types when assigning values to a range in code (PGSQL).

So if i declare this : e.g. 

declare tx tstzrange := '[today, tomorrow)' ;

I get the variable tx as expected with the Inclusive '[' lower bound and exclusive upper ')' bound.  

But if I attempt to reassign the value in code within pgsql I can do this simply, only with '(' syntax for the lower bound i.e. with an exclusive lower bound, e.g so this works:-

tx= (Timestamptz 'today', timestamptz 'now' + interval '1 hour');

but if I try

            tx= [Timestamptz 'today', timestamptz 'now' + interval '1 hour');

this will have syntax errors - as the hidden 'select [' upsets the parser.   I've tried to include a '[)' in variations of the _expression_, but just get various syntax errors..

I've tried many combinations and I can get it to work using casts and concatenations, e.g. :- 

 tx = CONCAT('[', 'today'::Timestamptz,',',('now' ::Timestamptz + interval '1 hour'):: timestamptz , ')'):: tstzrange ;

 

works but I can't help thinking that I'm missing something much simpler and more elegant.

How should this actually be done?

Thanks in advance for your advice.

Ron

Stay safe everyone.

here's an example script to show what I mean:-

do
$$
DECLARE

tx tstzrange := '[today, tomorrow)' ;

answer text;

BEGIN

RAISE NOTICE 'Start %', tx;

answer = tx @> 'today'::Timestamptz;

RAISE NOTICE 'today  %', answer;

answer = tx @> 'tomorrow'::Timestamptz;

RAISE NOTICE 'tomorrow  %', answer;

-- ( works
-- tx= (Timestamptz 'today', timestamptz 'now' + interval '1 hour');
-- [ doesn't work
-- tx= [Timestamptz 'today', timestamptz 'now' + interval '1 hour');
-- working around the parser??
tx = CONCAT('[', 'today'::Timestamptz,',',('now' ::Timestamptz + interval '1 hour'):: timestamptz , ')'):: tstzrange ;

RAISE NOTICE 'reassign  %', tx;

answer = tx @> 'today'::Timestamptz;

RAISE NOTICE 'today  %', answer;

answer = tx @> 'now'::Timestamptz;

RAISE NOTICE 'now    %', answer;

END;

$$