thanks for the answer.
Set width works.

However it still does not work when alias is used.
For example,

long_field_name varchar(30);

Set width long_field_name 10;
select long_field_name from test; // => display 10 char

Set width long_field_name 10;
select long_field_name lfn from test; // => display 30 char

Is it also possible the latter case print 10 chars only?

thx