How to auto increment data on new record insertion

I would like to add a user defined column which will auto increment on new record insertion, how should I do this? so that it runs on h2, mysql

@Entity public class Parent {

@OneToMany List<Child> children;

}

@Entity public class Child {
    int sortOrder;
}

e.g. Parent1 has Child{1, 2, 3}
Parent2 has {1, 2}

Note: Values within each Parent needs to be auto incre开发者_如何学JAVAmented not outside.

Set the Id type as identity, and the DB tbale should handle the Identity insertion.

sample,

<id
            name="dayTypeId"
            column="Day_Type_ID"
            type="int">

            <generator class="identity">
            </generator>
        </id>

The database handles this, not Hibernate. You need auto_increment surrogate primary keys in your tables.