Database - Database Redesign Questions and Answers

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Q1
 Which of the following SQL statements are helpful in database redesign?
  • A Correlated subqueries only
  • B EXISTS/NOT EXISTS expressions only
  • C Both of the above are helpful
  • D None of the above are helpful.
Answer: Option C
Q2
What SQL command can be used to delete columns from a table?
  • 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
Answer: Option C
Q3
Database redesign is not terribly difficult if the:
  • A database is structured.
  • B database is well-designed.
  • C database has no data.
  • D database is relatively small.
Answer: Option C
Q4
Which SQL-92 standard SQL command can be used to change a table name?
  • A RENAME TABLE
  • B CHANGE TABLE
  • C ALTER TABLE
  • D None of the above is correct.
Answer: Option D
Q5
The process of reading a database schema and producing a data model from that schema is known as:
  • A data modeling.
  • B database design.
  • C reverse engineering.
  • D None of the above is correct.
Answer: Option C
Q6
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
Q7
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
Q8
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
Q9
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
Q10
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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