Exam 8: Database Redesign

The use of a double nested set of NOT EXISTS SELECT statements is so rare that even if you are a professional database developer you will probably never see it used.

EXISTS and NOT EXISTS are actually just another form of correlated subqueries.

Database redesign is equally difficult whether or not the database has data in it.

To add a NULL column to a table,we simply use the MODIFY TABLE statement.

What is reverse engineering and how well does it work?

To drop a nonkey column from a table,no preliminary steps are needed and we can simply use the ALTER TABLE DROP COLUMN statement.

The use of a double nested set of NOT EXISTS SELECT statements is a famous pattern in SQL use.

Although correlated subqueries are useful in database redesign,they cannot be used to verify functional dependencies.

Which of the following different copies of the database schema is/are typically used in the database redesign process?

The data model produced by reverse engineering is a true conceptual schema.

When increasing cardinalities from 1:N to N:M,which of the following steps is/are included in the process? (The order of the steps listed below is not relevant,only the steps themselves. )

There is a common trap in writing a correlated subquery,which will cause no rows to ever be displayed in the results.

What is the process for adding a NOT NULL column to a table?

The data model produced by reverse engineering may include some entities that should not appear in the data model.

When using a double nested set of NOT EXISTS SELECT statements,a row that does not match any row matches every row.

Correlated subqueries can be used to verify functional dependencies.

In the SQL statement: SELECT S1.CustName,S1.SalesRepNo FROM SALES S1; the "S1" is called an alias.

Database redesign is fairly easy when ________.

A means must be created to recover all test databases to their original state during the redesign testing process.

When running a correlated subquery,the DBMS always uses ________.