hallo i've a problem with mapping a propery a want a dateproperty only for inserted hibernate insert a database datetime typical(sql server getDate()) but i dont have understand how config mapping file

<myclass .... >

<property name="CreationDate"
column="CreationDate"
type="DateTime"
not-null="true"
??? i 've tried with formula ...
/>
<prope
</myclass>
thanks for help

i must only to use a custom sql???
example
<sql-insert>INSERT INTO PERSON (NAME, ID) VALUES ( UPPER(?), ? )</sql-insert>