Important:
Retrieves a list of distinct values for a given field for all items that match the query, without duplicates.
As with queryDataItems(), this function retrieves items based on the filtering, sorting, and paging preferences provided. However, this function does not return the full items that match the query. Rather, for items that match the query, it returns all unique values in the field specified in fieldName. If more than one item has the same value in that field, that value appears only once.