Which statement is true regarding the UNION operator?
A.
By default, the output is not sorted.
B.
Null values are not ignored during duplicate checking.
C.
Names of all columns must be identical across all select statements.
D.
The number of columns selected in all select statements need not be the same.
Explanation:
For the UNION operator the nulls values are not ignored during duplicate checking.
Incorrect:Not A: The UNION operator implicitly sorts the output.
Not D: Each SQL SELECT statement within the UNION query must have the same number of fields in the
result sets with similar data types.