Select SPACE(1) FROM mytable UNION SELECT cName FROM someothertableThe size of the result column would be equal the lenght of cName in either case.
SELECT cName FROM mytable UNION SELECT cName FROM someothertableresults in error 1851 if cName is C(10) in mytable and C(1) in someothertable (i.e., smaller but not identical).
SELECT cName FROM mytable UNION SELECT SPACE(1) FROM someothertablealthough the result is not necessarily what one would expect.