Database Redesign problems
- 1. To drop a column that is used as a foreign key, first:
Options- A. drop the primary key.
- B. drop the table containing the foreign key..
- C. drop the foreign key constraint.
- D. All of the above must be done. Discuss
Correct Answer: drop the foreign key constraint.
- 2. Before any changes to database structure are attempted one should first:
Options- A. clearly understand the current structure and contents of the database only.
- B. test any changes on a test database only.
- C. create a complete backup of the operational database only.
- D. All of the above should be done. Discuss
Correct Answer: All of the above should be done.
- 3. How many copies of the database schema are typically used in the redesign process?
Options- A. One
- B. Two
- C. Three
- D. Four Discuss
Correct Answer: Three
- 4. Changing cardinalities in a database is:
Options- A. a common database design task.
- B. a rare database design task, but does occur.
- C. a database design task that never occurs.
- D. is impossible to do, so a new database must be constructed and the data moved into it. Discuss
Correct Answer: a common database design task.
- 5. Which is not true of a correlated subquery?
Options- A. EXISTS/NOT EXISTS is a form of a correlated subquery.
- B. The processing of the SELECT statements is nested.
- C. They can be used to verify functional dependencies.
- D. They are very similar to a regular subquery. Discuss
Correct Answer: They are very similar to a regular subquery.
- 6. The process of reading a database schema and producing a data model from that schema is known as:
Options- A. data modeling.
- B. database design.
- C. reverse engineering.
- D. None of the above is correct. Discuss
Correct Answer: reverse engineering.
- 7. Because of the importance of making data model changes correctly, many professionals are ________ about using an automated process for database redesign.
Options- A. optimistic
- B. skeptical
- C. ambivalent
- D. None of the above is correct. Discuss
Correct Answer: skeptical
- 8. Which of the following modifications may not succeed?
Options- A. Changing a column data type from char to date
- B. Changing a column data type from numeric to char
- C. Both of the above actions should succeed.
- D. Neither of the above actions will succeed. Discuss
Correct Answer: Changing a column data type from char to date
- 9. What SQL command will allow you to change the table STUDENT to add the constraint named GradeCheck that states that the values of the Grade column must be greater than 0?
Options- A. ALTER TABLE STUDENT ALTER CONSTRAINT GradeCheck (Grade > 0);
- B. ALTER TABLE STUDENT ADD CONSTRAINT GradeCheck (Grade > 0);
- C. ALTER TABLE STUDENT ADD CONSTRAINT GradeCheck CHECK (Grade > 0);
- D. None of the above is correct. Discuss
Correct Answer: ALTER TABLE STUDENT ADD CONSTRAINT GradeCheck CHECK (Grade > 0);
- 10. Database redesign is not terribly difficult if the:
Options- A. database is structured.
- B. database is well-designed.
- C. database has no data.
- D. database is relatively small. Discuss
Correct Answer: database has no data.
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