In general if you want rows that don’t exist in another table, then LEFT JOIN the other table and WHERE … IS NULL to a column on the second table. Also you mentioned that you don’t want rows where process.id_string is NULL. SELECT p.name, p.id_string FROM process p LEFT JOIN value_search v ON v.id_string = … Read more
indicator = True in merge command will tell you which join was applied by creating new column _merge with three possible values: left_only right_only both Keep right_only and left_only. That is it. outer_join = TableA.merge(TableB, how = ‘outer’, indicator = True) anti_join = outer_join[~(outer_join._merge == ‘both’)].drop(‘_merge’, axis = 1) easy! Here is a comparison with … Read more
select * from a where id not in (select a_id from b) Or like some other people on this thread says: select a.* from a left outer join b on a.id = b.a_id where b.a_id is null