Datatypes, Length, Precision, Scale, and Nulls - Quiz Explanation

The answers you selected are indicated below, along with text that explains the correct answers.

1.	What is the relationship between the amount of disk space required between a unicode and non-unicode datatype? Please select the best answer.
	A.	Answer: Unicode takes twice as much space as non-unicode.
	B.	Non-unicode takes twice as much space as unicode.
	C.	Unicode takes four times as much space as non-unicode.
	D.	Non-unicode takes four times as much space as unicode.
	The correct answer is A. A unicode datatype requires twice as much space as a non-unicode datatype. Therefore, B is incorrect. C and D are both incorrect because neither datatype takes four times as much space.

2.	For column EmployeeID, you try to specify a datatype of Int with a length of 4, but you receive an error. Other columns do not give you an error. What is the possible reason for this error? Please select the best answer.
	A.	EmployeeID is an invalid column name.
	B.	EmployeeIDs cannot have an Int datatype.
	C.	You do not have correct permissions on the table.
	D.	You cannot specify a length with an Int datatype.
	The correct answer is D. The Int datatype does not allow you to specify a length; the length is fixed. A is incorrect because EmployeeID is a valid column name. B is incorrect because any column name can be of any datatype. C is incorrect because you must have correct permissions if other columns do not produce errors.

3.	Which of the following is equivalent to null? Please select the best answer.
	A.	0
	B.	An empty string
	C.	The absence of a value
	D.	The word “NULL”
	The correct answer is C. The absence of a value is the same thing as a null value. A is incorrect because zero is not the same thing as null. B is incorrect because an empty string is not the same thing as null. D is incorrect because the word “NULL” is not the same as null.