9. Which statement is true regarding the INTERSECT operator?
A. It ignores NULL values.
B. Reversing the order of the intersected tables alters the result.
C. The names of columns in all SELECT statements must be identical.
D. The number of columns and data types must be identical for all SELECT statements in the query.
Question Analysis: Which of the following statements about intersection operations is true?
A: The intersection operation ignores Null (incorrect, the intersection operation does not ignore Null values)
B: exchange the order of the two tables. The result of the intersection is different (incorrect, the result of the intersection is irrelevant to the order of the table)
C: In all Select statements, the field names must be the same (incorrect, the field names can be different, but the number of fields and data type must be consistent)
D: In all Select statements, the number of fields and data type must be the same (correct ).