database - vb.net comparing two databases then insert or delete

Question

in vb.net how would you loop through database1 to check that all records in database2 exist in Database1 and the other way areound if a record exist in database1 and doesnt exist in database2 then delete it from database1. so database2 is my reference

how can i do this using queries, also does it have to include nested looping?

note that the records are not in the same order

Thanks

Answer 1

このクエリは、テーブルのローカル バージョンにないアタッチされたテーブルのすべての行を返します。

SELECT * FROM attachedTable 
WHERE col1 NOT IN( SELECT lt.col1 FROM localTable as lt)

これは逆のことを行い、リモート テーブルで一致しないローカル テーブルのすべての行を返します。

SELECT * FROM localTable 
WHERE col1 NOT IN( SELECT rt.col1 FROM attachedTable As rt)