Hibernation and schema update when column type changes

I have Hibernate to set up my entities. For a developer environment, I want Hibernate to handle schema updates (mostly some add new columns, delete or edit column types). When adding a new column, Hibernate will add it. Removing a field from an object will not remove the column from the database. I have read in some posts that this is normal behavior. But the problem was caused when I tried to change the field type of the object:

@Entity
class Person {

    String lastName; //This is the new column
}

      

        
        
        
      

    

This caused Hibernate to add a VARCHAR (255) column with default NULL and NOT NULL as YES.

There was already one record in the database (I'm testing the behavior), so Hibernate added a column with the existing behavior with an empty string value. I did not add column initialization in the entity constructor.

Changing the column type to int

has failed. Hibernate brought up IllegalArgumentException

trying to add a Null value to an int field.

I thought Hibernate would delete the column, recreate it and add a Null value without issue (since int fields can be NULL). Is it good practice to always give a default in the column name? Perhaps in a function with PrePersist?

@PrePersist
public void prePersist(){
    this.lastName = 5; //after changing lastName to int.
}

      

        
        
        
      

    

I want to add here that even in development we don't want to give up the table. We want to keep the current values.