Which of the following is not true about primary keys?
A) Primary keys cannot be null.
B) Primary keys must be unique.
C) Primary keys must be a single attribute.
D) Primary keys are used to represent relationships.
E) Primary keys can be defined using an SQL CONSTRAINT phrase.
Which of the following is not true of database recovery through reprocessing?
A) Reprocessing makes use of a database save.
B) Reprocessing takes the same amount of time as did processing in the first place.
C) Reprocessing will always return the database to its exact previous state.
D) Reprocessing requires a record of all transactions since the last time the database
E) All of the above are true of reprocessing.