To encrypt columns in existing tables, use the modify column option on the alter table statement with the encrypt clause:
alter table table_name modify column_name [encrypt [with [[database.][owner].]keyname]]
where keyname identifies a key created using create encryption key. The creator of the table must have select permission on keyname. If keyname is not supplied, Adaptive Server looks for a default key created using the as default clause on the create encryption key.
See the Reference Manual: Commands.
There are restrictions on modifying encrypted columns:
You cannot modify a column for encryption or decryption on which you have created a trigger. You must:
Drop the trigger.
Encrypt or decrypt the column.
Re-create the trigger.
You cannot change an existing encrypted column, modify a column for encryption or decryption on a table, or modify the type of an encrypted column if that column is a key in a clustered or placement index. You must:
Drop the index.
Alter the table/modify the type of column.
Re-create the index.
You can alter the encryption property on a column at the same time you alter other attributes. You can also add an encrypted column using alter table.
For example:
alter table customer modify custid null encrypt with cc_key alter table customer add address varchar(50) encrypt with cc_key
