I was able to successfully include a DISTINCT clause within the LISTAGG function by using this syntax:
SELECT LISTAGG(DISTINCT <measure expression>, <delimiter expression>) WITHIN GROUP… etc ...
You can find more information on the [syntax of LISTAGG here](https://community.denodo.com/docs/html/browse/8.0/en/vdp/vql/appendix/syntax_of_condition_functions/analytic_functions_window_functions#listagg).
However in order for this to work, I suggest you to check this prerequisite: when using the LISTAGG function, bear in mind that the Denodo Platform delegates the execution of the query to the underlying data source, so I would ensure that that data source supports LISTAGG.
If your data source doesn’t support the use of LISTAGG, I suggest you try using the [GROUP_CONCAT function](https://community.denodo.com/docs/html/browse/6.0/vdp/vql/appendix/syntax_of_condition_functions/aggregation_functions#group-concat) as an alternative, which works similarly to LISTAGG.
Hope this helps!