1) This short version of the auction table contains five rows, each with its own unique, non-NULL value for the auction_id table
2) A user adds a new row to the auction table that has a value for the auction_id column unique to the table.
3) The row is successfully inserted into the table.
4) A user attempts to insert a row into the auction table that has a non-unique value for the auction_id column.
5) The INSERT operation fails with an error, because a unique constraint has been violated.
6) A user tries to update a row, but makes the value of the auction_id NULL.
7) The UPDATE operaiton fails with an error, because the non-NULL constraint has been violated.