java - What hibernate do with unmapped column? -

suppose there class that:

public class entity {     private long id;     private string name; } 

and table 3 columns: id, name , address.

create table entity (     id number(9,0),     name varchar2(255),     address varchar2(1000), 

then en insert performed:

insert entity (id, name, address) values (1, "a", "b") 

then load , update hibernate entity:

session session = ... entity entity = session.get(entity.class, 1); 

then update name , save again:

entity.setname("newname"); session.save(entity); 

so address column value - null or b? hibernate provide stgrategies such situations or have add address field entity , mark @column(updatable=false, insertable = false)?

if put following properties in persistence.xml(or have defined hibernate properties)

<property name="hibernate.show_sql" value="false"/> <property name="hibernate.format_sql" value="false"/> 

then see queries executed hibernate when server run in debug mode logged configured debug.

if entity

public class entity {     private long id;     private string name;     private string secondname;     //getters & setters } 

then executing below hql

select e entity e e.id = 121 

would produce results similar to

select entity0_.id        id1_63_,         entity0_.name      name6_63_,         entity0_.secondname secondname6_63_,    yout_db.entity entity0_   entity0_.id = 121 

you see here select * entity not executed instead fields class fetched , added query. if have ignored field db not taking part in queries.

for select-update same thing happens.

entity.setname("newname"); session.save(entity); 

below formatted query if update entity:

update your_db.entity  set    name = ?        secondname = ?  id = ? 

this query executed if 1 field changed.