NVL function's strange behaviour

Question

Hi,
I have a sql statement (listed below) that uses NVL function which returns either the business name of branch name depending on whether the business name is null or not. It also uses the branch_name pl/sql function that returns the name of the branch.
What I found strange was that it executes the branch_name function even when the business_name is not null. It was my understanding that nvl returns expr1 if it's not null, and expr2 if expr1 is null. I don't want it to execute the branch_name function if business_name exists. Is it possible using NVL, or do I need to use DECODE to achieve that? p_record_id is a parameter that I pass to the function containing the sql statement e.g., p_record_id=10.
SELECT nvl( business_name, branch_name( p_record_id) ) "Name"
FROM entity
WHERE record_id = p_record_id;
Thanks
Vic

Answer 1

Marc,
Thanks for looking into it.
I just ran the code using DECODE and it seems that it executes the function only when the condition is true, which is exactly what I want. It won't execute the function if the condition is false, e.g., in the code below if the business_name is null then it executes the branch_name function, other wise it returns the business_name.
SELECT DECODE ( business_name,
null, branch_name( p_record_id ),
business_name ) "Name"
FROM entity
WHERE record_id = p_record_id;
Vic