Quiz Discussion

Which of the following is correct

• 1]

  a SQL query automatically eliminates duplicates

• 2]

  SQL permits attribute names to be repeated in the same relation

• 3]

  a SQL query will not work if there are no indexes on the relations

• 4]

  None of these

Which of the following is a legal expression in SQL?

• 1]

  SELECT NULL FROM EMPLOYEE;

   

• 2]

  SELECT NAME FROM EMPLOYEE;

   

• 3]

  SELECT NAME FROM EMPLOYEE WHERE SALARY = NULL;

   

• 4]

  None of the above

   

What is an advantage of placing computations in SQL views

• 1]

  To save users from having to write an expression

• 2]

  To ensure that the results are consistent

• 3]

  To accomplish both of the above

• 4]

  None of the above

Which of the following is an advantage of view?

• 1]

  Data security

• 2]

  Derived columns

• 3]

  Hiding of complex queries

• 4]

  All of the above

The SQL ALTER statement can be used to

• 1]

  Change the table structure

• 2]

  Change the table data

• 3]

  Add rows to the table

• 4]

  Delete rows from the table

Which of the following is an SQL trigger supported by Oracle?

• 1]

  BEFORE

• 2]

  AFTER

• 3]

  INSTEAD OF

• 4]

  All of the above

Count function in SQL returns the number of

• 1]

  Values

• 2]

  Distinct values

• 3]

  Groups

• 4]

  Columns

‘AS’ clause is used in SQL for

• 1]

  Selection operation

• 2]

  Rename operation

• 3]

  Join operation

• 4]

  Projection operation

A report generator is used to

• 1]

  update files

• 2]

  print files on paper

• 3]

  data entry

• 4]

  delete files

A reason for using an SQL view to hide columns is

• 1]

  to simplify a result only

• 2]

  to prevent the display of sensitive data only

• 3]

  to accomplish both of the above

• 4]

  None of the above