使用查找功能更新Excel电子表格

Ive watched an hour on lookup functions and dug through forums but cannot figure out how to update an existing database with new info from an online source (rather than using cntrl f, then cntrl c/v hundreds of times every few days). My strategy is to have the old database table next to the new database table (the old table includes all new table info except whether or not a row has been tempered with). I want the old table to update with a column that conditionally formats with a yes if the new table from online shows particular rows have been tampered with. I'm assuming in need to incorporate the search function with lookup but i'm admittedly and absolute noob.Ive watched an hour on lookup functions and dug