Database - Database Redesign MCQs Part
1. Which of the following SQL statements are helpful in database redesign?
A.
Correlated subqueries only
Correlated subqueries only
B.
EXISTS/NOT EXISTS expressions only
EXISTS/NOT EXISTS expressions only
C.
Both of the above are helpful
Both of the above are helpful
D.
None of the above are helpful.
None of the above are helpful.
Answer Option C
2. What SQL command can be used to delete columns from a table?
A.
MODIFY TABLE TableName DROP COLUMN ColumnName
MODIFY TABLE TableName DROP COLUMN ColumnName
B.
MODIFY TABLE TableName DROP ColumnName
MODIFY TABLE TableName DROP ColumnName
C.
ALTER TABLE TableName DROP COLUMN ColumnName
ALTER TABLE TableName DROP COLUMN ColumnName
D.
ALTER TABLE TableName DROP ColumnName
ALTER TABLE TableName DROP ColumnName
Answer Option C
3. Database redesign is not terribly difficult if the:
A.
database is structured.
database is structured.
B.
database is well-designed.
database is well-designed.
C.
database has no data.
database has no data.
D.
database is relatively small.
database is relatively small.
Answer Option C
4. Which SQL-92 standard SQL command can be used to change a table name?
A.
RENAME TABLE
RENAME TABLE
B.
CHANGE TABLE
CHANGE TABLE
C.
ALTER TABLE
ALTER TABLE
D.
None of the above is correct.
None of the above is correct.
Answer Option D
5. The process of reading a database schema and producing a data model from that schema is known as:
A.
data modeling.
data modeling.
B.
database design.
database design.
C.
reverse engineering.
reverse engineering.
D.
None of the above is correct.
None of the above is correct.
Answer Option C
6. Before any changes to database structure are attempted one should first:
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.
Answer Option D
7. Which of the following modifications may not succeed?
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.
Answer Option A
8. How can you find rows that do not match some specified condition?
A. EXISTS
B. Double use of NOT EXISTS
C. NOT EXISTS
D. None of the above is correct.
Answer Option B
9. A regular subquery can be processed:
A. from the top down.
B. from the bottom up.
C. by nesting.
D. None of the above is correct.
Answer Option B
10. What SQL command can be used to add columns to a table?
A. MODIFY TABLE TableName ADD COLUMN ColumnName
B. MODIFY TABLE TableName ADD ColumnName
C. ALTER TABLE TableName ADD COLUMN ColumnName
D. ALTER TABLE TableName ADD ColumnName
Answer Option D
11. The EXISTS keyword will be true if:
A. any row in the subquery meets the condition only.
B. all rows in the subquery fail the condition only.
C. both of these two conditions are met.
D. neither of these two conditions is met.
Answer Option A
12. Changing cardinalities in a database is:
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.
Answer Option A
13. The NOT EXISTS keyword will be true if:
A. any row in the subquery meets the condition.
B. all rows in the subquery fail the condition.
C. both of these two conditions are met.
D. neither of these two conditions is met.
Answer Option B
14. The data model that is produced from reverse engineering is:
A. a conceptual model.
B. an internal model.
C. a logical model.
D. None of the above is correct.
Answer Option D
15. To drop a column that is used as a foreign key, first:
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.
Answer Option C
16. 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?
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.
Answer Option C
17. Which is not true of a correlated subquery?
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.
Answer Option D
18. A tool that can help designers understand the dependencies of database structures is a:
A. dependency graph.
B. data model.
C. graphical display.
D. None of the above is correct.
Answer Option A
19. How many copies of the database schema are typically used in the redesign process?
A. One
B. Two
C. Three
D. Four
Answer Option C
20. Because of the importance of making data model changes correctly, many professionals are ________ about using an automated process for database redesign.
A. optimistic
B. skeptical
C. ambivalent
D. None of the above is correct.
Answer Option B
6. Before any changes to database structure are attempted one should first:
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.
Answer Option D
7. Which of the following modifications may not succeed?
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.
Answer Option A
8. How can you find rows that do not match some specified condition?
A. EXISTS
B. Double use of NOT EXISTS
C. NOT EXISTS
D. None of the above is correct.
Answer Option B
9. A regular subquery can be processed:
A. from the top down.
B. from the bottom up.
C. by nesting.
D. None of the above is correct.
Answer Option B
10. What SQL command can be used to add columns to a table?
A. MODIFY TABLE TableName ADD COLUMN ColumnName
B. MODIFY TABLE TableName ADD ColumnName
C. ALTER TABLE TableName ADD COLUMN ColumnName
D. ALTER TABLE TableName ADD ColumnName
Answer Option D
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