Convert listdata into CSV string grouped

[#1]

I am looking for a solution to convert list data into a CSV string grouped in this example on Contract_ID.

This is an example of the list data:

contract_ID	name	type
1	Paul	abc
1	Benno	def
2	kees	abc
2	Ron	ghi

required result:

1	Paul:abc, Benno:def
2	kees:abc, Ron:ghi

[Gysbert_Wassenaar · Accepted solution]

load contract_ID, concat( name & ':' & type, ',') as grouped

from ...source...

group by contract_ID;