CREATE VIEW TableStripped AS
SELECT AcolumnThatDoesntNeedStripping
, BcolumnThatDoesntNeedStripping
, ...
, SUBSTRING(columnA, 1, 20)
, SUBSTRING(columnB, 1, 20)
, SUBSTRING(columnC, 1, 20)
, ...
, SUBSTRING(columnZ, 1, 20)
y luego usa esa vista:
SELECT *
FROM TableStripped