One to many values relationship

Question

Hello Everyone ,
I am working on an exception management project.  I am having some difficulty showing one to many relationship from multiple tables . I used listagg function and was able to use show the one to many relationship via a select query . However , as our application maybe housed on sql-sever , i was told to find a workaround without the oracle specific function. I ll explain the relationship between exceptions and its ids
Exception 100 has 5 ids which has 2 distinct entity types
EXCEPTION  ID     ENTITY TYPE
100               1        SECURITY 
100               2        SECURITY
100               3        SECURITY
100               4        BOND
100               5        BOND
The desired output is
Exception        Entity_type
100                  Security,Bond
I have tried to use the case condition in select
case
when
count(distinct link.entity_type_id) > 1
then
null  ----------------- ( need to use something in select )
else
max(entity_type_def.name)
end
Is it possible to do the following
1) Use a subquery to get comma separated values ?
2) If option 1 is not possible, any function which can be used in both sql server and oracle ?

Answer 1

Trying to write a single piece of code to work on different platforms is a sure way to end up with lengthy, complicated and poorly performing code in a lot of cases.
You would be better having two versions of the code, one written for Oracle to utilize it's power to achieve the task and one written for SQL Server to utilize it's power to achieve the same.
PL/SQL and T-SQL are completely different languages, and whilst a lot of things are common amongst the SQL functionality, the more complex tasks tend to be better done using their own methods.
Could you write a single piece of SQL to work on both... yes, in this case I'm sure you could... but "should" you write a single piece of SQL to work on both is probably a better question to ask.