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- Question
Which of the following SQL statements are helpful in database redesign?
Options- A. Correlated subqueries only
- B. EXISTS/NOT EXISTS expressions only
- C. Both of the above are helpful
- D. None of the above are helpful.
- Correct Answer
- Both of the above are helpful
- 1. What SQL command can be used to delete columns from a table?
Options- A. MODIFY TABLE TableName DROP COLUMN ColumnName
- B. MODIFY TABLE TableName DROP ColumnName
- C. ALTER TABLE TableName DROP COLUMN ColumnName
- D. ALTER TABLE TableName DROP ColumnName Discuss
- 2. How can you find rows that do not match some specified condition?
Options- A. EXISTS
- B. Double use of NOT EXISTS
- C. NOT EXISTS
- D. None of the above is correct. Discuss
- 3. A regular subquery can be processed:
Options- A. from the top down.
- B. from the bottom up.
- C. by nesting.
- D. None of the above is correct. Discuss
- 4. The NOT EXISTS keyword will be true if:
Options- 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. Discuss
- 5. What SQL command can be used to add columns to a table?
Options- 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 Discuss
- 6. A tool that can help designers understand the dependencies of database structures is a:
Options- A. dependency graph.
- B. data model.
- C. graphical display.
- D. None of the above is correct. Discuss
- 7. The data model that is produced from reverse engineering is:
Options- A. a conceptual model.
- B. an internal model.
- C. a logical model.
- D. None of the above is correct. Discuss
- 8. The EXISTS keyword will be true if:
Options- 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. Discuss
- 9. Which SQL-92 standard SQL command can be used to change a table name?
Options- A. RENAME TABLE
- B. CHANGE TABLE
- C. ALTER TABLE
- D. None of the above is correct. Discuss
- 10. 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
Database Redesign problems
Search Results
Correct Answer: ALTER TABLE TableName DROP COLUMN ColumnName
Correct Answer: Double use of NOT EXISTS
Correct Answer: from the bottom up.
Correct Answer: all rows in the subquery fail the condition.
Correct Answer: ALTER TABLE TableName ADD ColumnName
Correct Answer: dependency graph.
Correct Answer: None of the above is correct.
Correct Answer: any row in the subquery meets the condition only.
Correct Answer: None of the above is correct.
Correct Answer: drop the foreign key constraint.
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