Re: Evaluation of if conditions

Daniel,

AFAIK there is no short-circuiting of evaluations in postgres and I don't think you can depend on the order they appear
into determine the order in which they are checked, although more knowledgable people may have better info than I ...
sothe rewritten form is the way to go. 

Greg Williamson
DBA
GlobeXplorer LLC

-----Original Message-----
From:    pgsql-sql-owner@postgresql.org on behalf of Daniel CAUNE
Sent:    Wed 9/6/2006 3:32 PM
To:    pgsql-sql@postgresql.org
Cc:
Subject:    [SQL] Evaluation of if conditions

Hi,

How does the IF statement evaluate conditions?  Does it evaluate conditions
following their declaration order from left to right?  In case of
or-conditions, does the IF statement stop evaluating conditions whenever a
first or-condition is true?

The following snippet seems to be invalid, which let me think that PL/PGSQL
evaluates all the conditions:
 IF (TG_OP = 'INSERT') OR    (OLD.bar = ...) THEN   statement END IF;

Should be rewritten as (for example):
 IF (TG_OP = 'INSERT') THEN   statement ELSIF (OLD.bar = ...) THEN   statement END IF;


Regards,

--
Daniel


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