Set field length in SQL View

All,
I have an SQL View where I am selecting only part of a character field
using the SUBSTR function in a CTE, then using the derived field in a Group
By for the final select.
Part of the code is: SubStr( COALESCE(A.UDFBVALUE,' '), 1, 10) SCHEDB,

My problem is that when I look at the file definition, the field SCHEDB is
defined as :
Data Field Buffer
Field Type Length Length
SCHEDB CHAR 40 42

What do I need to do to get this field defined as CHAR 10?

Thanks,