text columns can be converted to:
[n]char
[n]varchar
unichar
univarchar
unitext columns can be converted to:
[n]char
[n]varchar
unichar
univarchar
binary
varbinary
image columns can be converted to:
varbinary
binary
You cannot modify char, varchar, unichar, and univarchar datatype columns to text or unitext columns. If you are converting from text or unitext to char, varchar, unichar, or univarchar, the maximum length of the column is governed by page size. If you do not specify a column length, alter table uses the default length of one byte. If you are modifying a multibyte character text, unitext, or image column, and you do not specify a column length that is sufficient to contain the data, Adaptive Server truncates the data to fit the column length.
