QUIZ ON SQL

  Primary key can be?

• NULL

• NOT NULL

• Both NULL and NOT NULL

• Depends on situation

Which of the following commands is used to delete all rows and free up space from a table?

• TRUNCATE

• DROP

• DELETE

• ALTER

Which of the following commands are a part of Data Control Language?

• Revoke

• Grant

• Both A and B

• None of the above

Which SQL constraint do we use to set some value to a field whose value has not been added explicitly?

• UNIQUE

• NOT NULL

• DEFAULT

• CHECK

  During transaction before commit which of the following statements is done  automatically in case of shutdown?

• Rollback

• Commit

• View

• Flashback

   Which of the following is not a SQL command?

• DELETE

• ORDER BY

• SELECT

• WHERE

Which of the following matches the definition given below:

It is an artificial key that aims to uniquely identify each record.

• Primary Key

• Foreign Key

• Surrogate Key

• Composite Key

  Which of the following commands are used to put a restriction on the number of rows returned from a query?

•   LIMIT

• LIKE

• WHERE

•   GROUP BY

What does the following code snippet do?

• Performs an undo operation on the delete operation.

• Deletes the rows from the table where AGE = 16

• Deletes the entire table

• None of the above

Which of the following is not a valid aggregate function?

• count()

• Sum()

• Avg()

• None of the above