Database - Database Redesign Questions and Answers
Database Redesign focuses on restructuring existing databases to improve performance, scalability, or compliance with new requirements. It’s a frequently asked topic in aptitude questions and answers with explanations for placement tests and technical interviews. Understanding normalization, schema migration, and data integrity ensures smooth database evolution. For companies like TCS, Capgemini, and Infosys, this is a key skill area tested in DBMS aptitude questions with solutions PDF. By mastering redesign strategies, students can optimize legacy systems, integrate modern technologies, and enhance query performance efficiently—essential for both academic excellence and real-world applications.
Focus on redesigning databases for optimization. Complement with normalization and ER modeling
Database - Database Redesign
1. Which of the following SQL statements are helpful in database redesign?
- Correlated subqueries only
- EXISTS/NOT EXISTS expressions only
- Both of the above are helpful
- None of the above are helpful.
2. What SQL command can be used to delete columns from a table?
- MODIFY TABLE TableName DROP COLUMN ColumnName
- MODIFY TABLE TableName DROP ColumnName
- ALTER TABLE TableName DROP COLUMN ColumnName
- ALTER TABLE TableName DROP ColumnName
3. Database redesign is not terribly difficult if the:
- database is structured.
- database is well-designed.
- database has no data.
- database is relatively small.
4. Which SQL-92 standard SQL command can be used to change a table name?
- RENAME TABLE
- CHANGE TABLE
- ALTER TABLE
- None of the above is correct.
5. The process of reading a database schema and producing a data model from that schema is known as:
- data modeling.
- database design.
- reverse engineering.
- None of the above is correct.
6. Before any changes to database structure are attempted one should first:
- clearly understand the current structure and contents of the database only.
- test any changes on a test database only.
- create a complete backup of the operational database only.
- All of the above should be done.
7. Which of the following modifications may not succeed?
- Changing a column data type from char to date
- Changing a column data type from numeric to char
- Both of the above actions should succeed.
- Neither of the above actions will succeed.
8. How can you find rows that do not match some specified condition?
- EXISTS
- Double use of NOT EXISTS
- NOT EXISTS
- None of the above is correct.
9. A regular subquery can be processed:
- from the top down.
- from the bottom up.
- by nesting.
- None of the above is correct.
10. What SQL command can be used to add columns to a table?
- MODIFY TABLE TableName ADD COLUMN ColumnName
- MODIFY TABLE TableName ADD ColumnName
- ALTER TABLE TableName ADD COLUMN ColumnName
- ALTER TABLE TableName ADD ColumnName