liittyä(To connect one or more people together in a conversation); liittää(A connection between multiple tables where records from related fields that match are combined and shown as one record. Records that don't match may be included or excluded, depending on the type of join); liitä(To combine the contents of two or more tables and produce a result set that incorporates rows and columns from each table. Tables are typically joined using data that they have in common)
