Database Redesign(Engineering > Computer Science And Engineering > Database System ) Questions and Answers

Question 1. Database redesign is not terribly difficult if the:
  1.    database is well-designed.
  2.    database is structured.
  3.    database has no data.
  4.    database is relatively small.
Explanation:-
Answer: Option C. -> database has no data.
Question 2. Which SQL-92 standard SQL command can be used to change a table name?
  1.    None of these
  2.    CHANGE TABLE
  3.    RENAME TABLE
  4.    ALTER TABLE
Explanation:-
Answer: Option A. -> None of these
Question 3. What SQL command can be used to delete columns from a table?
  1.    ALTER TABLE TableName DROP COLUMN ColumnName
  2.    MODIFY TABLE TableName DROP ColumnName
  3.    ALTER TABLE TableName DROP ColumnName
  4.    MODIFY TABLE TableName DROP COLUMN ColumnName
Explanation:-
Answer: Option A. -> ALTER TABLE TableName DROP COLUMN ColumnName
Question 4. Which of the following SQL statements are helpful in database redesign?
  1.    Correlated subqueries only
  2.    None of these
  3.    Both of the above are helpful
  4.    EXISTS/NOT EXISTS expressions only
Explanation:-
Answer: Option C. -> Both of the above are helpful
Question 5. The process of reading a database schema and producing a data model from that schema is known as:
  1.    database design.
  2.    data modeling.
  3.    None of these
  4.    reverse engineering.
Explanation:-
Answer: Option D. -> reverse engineering.
Question 6. Before any changes to database structure are attempted one should first:
  1.    All of these
  2.    create a complete backup of the operational database only.
  3.    test any changes on a test database only.
  4.    clearly understand the current structure and contents of the database only.
Explanation:-
Answer: Option A. -> All of these
Question 7. A regular subquery can be processed:
  1.    from the top down.
  2.    from the bottom up.
  3.    None of these
  4.    by nesting.
Explanation:-
Answer: Option B. -> from the bottom up.
Question 8. Which of the following modifications may not succeed?
  1.    Both of the above actions should succeed
  2.    Changing a column data type from char to date
  3.    Neither of the above actions will succeed
  4.    Changing a column data type from numeric to char
Explanation:-
Answer: Option B. -> Changing a column data type from char to date
Question 9. How can you find rows that do not match some specified condition?
  1.    None of these
  2.    Double use of NOT EXISTS
  3.    NOT EXISTS
  4.    EXISTS
Explanation:-
Answer: Option B. -> Double use of NOT EXISTS
Question 10. What SQL command can be used to add columns to a table?
  1.    ALTER TABLE TableName ADD ColumnName
  2.    MODIFY TABLE TableName ADD COLUMN ColumnName
  3.    MODIFY TABLE TableName ADD ColumnName
  4.    ALTER TABLE TableName ADD COLUMN ColumnName
Explanation:-
Answer: Option A. -> ALTER TABLE TableName ADD ColumnName
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