Mediawiki 1.39.4, PHP 8.1.25, MariaDB 11.1. When #get_db_data is constructed like this (using SQL JOIN): {{#get_db_data: db=test |from=t1 |where=t1.c1='test' |join on=t1.c1=t2.id |data=t1c1=t1.c1 }} the resulting query is SELECT t1.c1 FROM t1 WHERE t1.c1='test' i.e. missing 'JOIN t2 ON t1.c1=t2.id'. Tested with ExternalData 3.1, 3.2 and Git master. Thanks for any attention to this. Šarūnas