Database Redesign Questions and Answers

Answer: B

Correct answer: False

Building realistic test databases is a substantial specialism in its own right, requiring data that exercises the boundary conditions, respects the constraints, and is large enough to reveal performance problems - while often being anonymised for privacy. It is a recognised and well-paid area of database work, not a dead end.

Answer: C

Correct answer: Three

Three copies are used: the operational schema, which is left untouched; a test copy on which the changes and their SQL are proved; and a copy carrying the proposed new design. Working with fewer means either testing against live data or having nowhere to develop the new structure, and the three-copy arrangement is what allows the change to be rehearsed completely before it is applied.

Answer: C

Correct answer: reverse engineering.

Reverse engineering works backwards from what exists: it reads the schema - tables, columns, keys, constraints - and produces a data model from it. Forward engineering runs the other way, generating a schema from a model. Reverse engineering is the first step in redesigning a database whose documentation is missing or has fallen out of step with what was actually built.

Answer: B

Correct answer: False

SQL-92 contains no rename command at all. RENAME TABLE is MySQL’s, and the other products each have their own, so a rename cannot be written portably. The standard-conforming route is to create the new table, copy the rows and drop the old one.

Answer: B

Correct answer: False

Three copies are used, not two: the operational schema, which is left alone; a test copy on which the changes are proved against representative data; and a copy carrying the proposed new design. With only two, either the testing is done against live data or there is nowhere to develop the new structure.