15. Consider this compound query:
select empno, hired from empunion allselect emp_id,hired,fired from ex_emp;The columns EMP.EMPNO and EX_EMP.EMP_ID are integer; the column
EMP.HIRED is timestamp; the columns EX_EMP.HIRED and EX_EMP.FIRED
are date. Why will the statement fail? (Choose the best answer.)
A. Because the columns EMPNO and EMP_ID have different names
B. Because the columns EMP.HIRED and EX_EMP.HIRED are different
data types
C. Because there are two columns in the first query and three columns in the
second query
D. For all of the reasons above
E. The query will succeed
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