How to tag content from external databases? I have an external database with a couple of hundred rows and columns. Is there a way in which I can tag content while or after I import the database to my drupal 7 website? Is there any module already contributed which could be used for this purpose?
by tagging you mean reference taxonomy terms ?

you could import those rows with the migrate module as nodes, with taxonomy reference (a normal taxonomy field), into your drupal DB.