Exam 8: Database Redesign

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

Because of the need to know the functional dependencies in a database,it is a good idea to create a dependency graph.

In the database redesign process,two SQL tools are useful for testing whether or not certain conditions or assumptions are valid: uncorrelated subqueries and EXISTS/NOT EXISTS.

Deleting tables and relationships is basically a matter of dropping foreign key constraints and then dropping the tables.

A dependency graph should include all of the following except ________.

The NOT EXISTS keyword will be true if any row in the subquery fails to meet the condition.

When decreasing cardinalities,there will always be ________.

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

Discuss workable data conversion and possible data loss when changing column data types during a database redesign.

The design produced by reverse engineering may be described as a table-relationship diagram.

The process of reading an actual database schema and producing a data model from that schema is called reverse engineering.

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

In order to minimize the need to change table names,some organizations have a policy that no user or application should ever employ the true name of a table,but use views as table aliases instead.

In the database redesign process,it is often useful to test whether certain conditions or assumptions are valid before proceeding with the redesign.

To add a NULL column to a table,we ________.

In the database redesign process,before proceeding with the redesign it is often useful to ________.

Adding new tables and relationships to a database is difficult.

Discuss the role of backup and test databases in database redesign.

To drop a primary key column from a table the primary key constraint must first be dropped,but this does not require that related foreign keys based on the column be dropped.

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