For every i,j in the sql procedure result, you want to obtain the distance and such route exists, right? If so, a parameter with following definition should work.

routeexists(i,j):= (distance(i,j) > 0)

so you do not need the last row in the mapping, but calculate the parameter after reading  from DB.

Thanks deannezhang, but the problems are:

1 - I have a stored procedure instead of a table

2 - My stored procedure only provide me the columns i and j. What means that if the combination (i, j) exists the route also exists.

That’s why I was asking about the compound set way to achieve this information.

I’m facing the same problem where I need to read from and write to a database table, which consists of only two columns, which form a relation (like the cities “from” and “to” in the above example). I tried using a relation (not a compound set), but when reading from the database table, the relation remains empty.

Is something like the following still supported in AIMMS?

"from" --> i_City,
"to" --> j_City,
("from","to") --> S_CityToCityRelation

Hi, @Benedikt. In order to read this table, I’d use database procedure and query attribute: 

select from,to,1 as relation from table

from → i_City
to → j_City

relation → P_YourParameter(i_City,j_City)

Then you can use this parameter to create your query and write to database.

I don’t quite remember if there is a better approach to this, maybe AIMMS team can help us further.

Thank you, @mateusarakawa, that’s a good idea! In order to write the relation to the table, I would probably need to construct a sql-insert-statement myself and use DirectSQL. I’m still wondering if there’s an “AIMMS-way” to do it.