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- Question
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.
- Correct Answer
- any row in the subquery meets the condition only.
- 1. 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
- 2. 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
- 3. 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. Discuss
- 4. 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
- 5. 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
- 6. 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
- 7. 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
- 8. 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
- 9. How many copies of the database schema are typically used in the redesign process?
Options- A. One
- B. Two
- C. Three
- D. Four Discuss
- 10. 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
Database Redesign problems
Search Results
Correct Answer: None of the above is correct.
Correct Answer: dependency graph.
Correct Answer: Both of the above are helpful
Correct Answer: ALTER TABLE TableName DROP COLUMN ColumnName
Correct Answer: Double use of NOT EXISTS
Correct Answer: None of the above is correct.
Correct Answer: drop the foreign key constraint.
Correct Answer: All of the above should be done.
Correct Answer: Three
Correct Answer: a common database design task.
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