How to use the query builder to modify an existing query

An existing query can easily be modified with the query builder.

Extract from the REST URL the dynamic part of the query which starts with the dataset code. E.g. from

http://ec.europa.eu/eurostat/wdds/rest/data/v2.1/json/en/nama_10_gdp?precision=1&na_item=B1GQ&unit=CLV05_MNAC&unit=CP_MEUR&unit=CP_MNAC&unitLabel=label

extract

nama_10_gdp?precision=1&na_item=B1GQ&unit=CLV05_MNAC&unit=CP_MEUR&unit=CP_MNAC&unitLabel=label

Copy and paste this in the query builder, then proceed with "Next"