Sorry, why transient attribute?
Use a model driven lov to set the attribute in the vo which is based on an eo.
Is it possible to use only the VO without defining the EO in the model ?
Yes, you can make and use read-only ViewObject, which is based on pure SQL statement (not based on entity)
If so, how do i declare the primary key attribute in the VO for accessing the attribute value by findbyKey.
Simply double-click on the attribute you want to be primary key, and check Key attribute check box