Any way to handle exceptions in PL/pgSQL ?

Is there any way to handle failed queries in PL/pgSQL?

<< I am aware that the example can be re-worded in a single query; This
is a question more on how to do the 'procedural' part >>

Example:
1st query
if OK, return result
2ne query
if OK, return result
return error message

Is it correct, that if a function fails, it returns null ??

-- Function: message_get(varchar)
CREATE FUNCTION message_get(varchar) RETURNS varchar AS '
DECLARE
p_key ALIAS FOR $1;
v_RetValue Message.MsgText%TYPE;
BEGIN
SELECT MsgText INTO v_RetValue
FROM User_Message
WHERE Value = p_Value;
-- if ok ??
RETURN v_RetValue;

SELECT Text INTO v_RetValue
FROM Sys_Message
WHERE Value = p_Value;
-- if ok ??
RETURN v_RetValue;

RETURN 'nothing found';
END;
' LANGUAGE 'plpgsql';

Cheers,

Jorg Janke (203) 445-9503 http://www.compiere.org
Smart ERP & CRM Business Solution for Distribution and Service globally
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