Re: How do I specify intervals in functions?

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От Rob Richardson
Тема Re: How do I specify intervals in functions?
Дата
Msg-id 04A6DB42D2BA534FAC77B90562A6A03D9A2272@server.rad-con.local
обсуждение исходный текст
Ответ на How do I specify intervals in functions?  ("Rob Richardson" <Rob.Richardson@rad-con.com>)
Список pgsql-general
I found my problem.  I trimmed down the function I was having trouble with to the following:
 
CREATE OR REPLACE FUNCTION recalculate_heating_time(int4)
  RETURNS int4 AS
$BODY$
declare
    ChargeNum   ALIAS for $1;
    ChargeRec    charge%rowtype;
    HeatingTime  int4;
    IntervalMinutes float4;
    NewRevisionTime timestamp;
    PredictedEndTime timestamp;
    Interval  interval;
    PredictedSpan interval;
    Message  varchar;
    EightHours  interval;
 
begin
    Message = '07:00:00'::varchar;
    EightHours = '08:00:00'::interval;
    return 1;
end;
This gave me the following error message:
ERROR:  syntax error at or near "$1" at character 22
QUERY:  SELECT  '08:00:00':: $1
CONTEXT:  SQL statement in PL/PgSQL function "recalculate_heating_time" near line 15
I stripped out all the declarations before Message, and the function loaded successfully. 
 
I'm primarily a C++/C# developer, and in those languages, there's no problem differentiating between "Interval" and "interval".  In the Postgres SQL dialect (and probably in all other SQL variants), the two words are treated identically.  The line where I declared a variable named "Interval" of type "interval" screwed everything up.
 
RobR
Using PostGreSQL 8.1 under Windows XP Pro


From: pgsql-general-owner@postgresql.org [mailto:pgsql-general-owner@postgresql.org] On Behalf Of Rob Richardson
Sent: Thursday, July 31, 2008 8:37 AM
To: pgsql-general@postgresql.org
Subject: [GENERAL] How do I specify intervals in functions?

Greetings!
 
In the help file under date and time functions, I see that intervals can be specified as "interval '3 hours' ".  In a PgAdmin SQL window, I can enter "select interval '3 hours' ", and it will return me "03:00:00", as expected.  I can also enter "select '3 hours'::interval", and get the same result.  Yet neither syntax works inside a function. 
 
declare
     ThreeHours interval;
begin
     ThreeHours = interval '3 hours';  -- throws a syntax error
     ThreeHours = '3 hours'::interval; -- also throws a syntax error
end;
 
So how do I specify an interval in a function?
 
Specifically, I'm trying to do something like the following:
 
    if NewRevisionTime < PredictedEndTime - '08:00:00'::interval then
 
Since both of the shown forms give syntax errors, how do I subtract eight hours from a time???
 
Thank you very much.
 
RobR, who posted this on the novice list but got no answers.
 

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