-421 THE OPERANDS OF A SET OPERATOR DO NOT HAVE THE SAME NUMBER OF COLUMNS

Explanation
  The operands of a set operator,
such as UNION, EXCEPT, or INTERSECT, must have the same number of
columns.

System action
  The statement cannot be processed.

Programmer response
  Correct the SQL statement
so that there are exactly the same number of columns.

SQLSTATE
  42826