A. True. When using set operators, the number and order of columns must be the same in all SELECT statements involved in the query. The data types of those columns must also be compatible.
E. True. The FOR UPDATE clause cannot be specified in a subquery or a SELECT statement that is combined with another SELECT statement by using a set operator.
B is incorrect because the column names do not need to match; only the number and data types of the columns must be compatible. C is incorrect because only the final SELECT statement in the sequence of UNION/INTERSECT/MINUS operations can have an ORDER BY clause. D is incorrect because, as of Oracle 12c, UNION ALL can be used with CLOB columns, but UNION, INTERSECT, and MINUS cannot.
[Reference: Oracle Database SQL Language Reference 12c, Set Operators - Set Operators, ]
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