how to make the filed Integer of java object null to null in sql instead 0

Question

Here is my modele

@Entity
public class Structure implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue
private Integer idt_structure;
private String name;
@ManyToOne
@JoinColumn(name="idt_parent_structure")
private Structure structure;
// Getters and setters
}

Example of input and outpu

Input

 public void save(){
 Structure structure = new Structure();
 structure.setName("structure");
 structure.setStructure(null);
 structureService.add(structure);
 }

Here is my Service

Transactional
@Service("structureService")
public class StructureServiceImpl implements IStructureService{
@Autowired
@Qualifier("structureDao")
private StructureDao structureDao;
private List<Structure> structures;
public StructureServiceImpl() {
 super();
}
@Override
public void addStructure(Structure structure) {
 structureDao.save(structure);
}
// getters and setters
}

Here is My DAO

@Repository
public class StructureDao extends GenericDaoHibernateImpl<Structure, Integer> {
@Autowired
@Qualifier("sessionFactory")
private SessionFactory sessionFactory;
@Autowired
public StructureDao(@Qualifier("sessionFactory") SessionFactory sessionFactory) {
 super(sessionFactory);
}
}

SQL SCHEMA TABLE Structure idt_structure int(11), name varchar(255), idt_parent_structure int(11). And all columns All columns can take the value null unless idt_structure

Output in datadase

sql schema : idt_structure, name , idt_parent_structure.

structure(1,name,0);

and i want to have output like this

structure(1,name,null);

The default value of an Integer is 0 And I want to have null in sql database for the idt_parent_structure column.

• assylias: Please show a minimal reproducible example. What is your database schema? How do you store the data in the DB? How do you generate the output? etc.
• ADS: Why do you want to see null in id field? In most cases it would be wrong
• Rodik: @assylias thank u for ur reply i update my post to see more details.
• ADS: please add structureDao.save, configuration of your ORM and DB schema. DB schema and configuration is important since it depends on not only code
• Rodik: @ADS i'm using GenericDaoHibernateImpl it's generic but u can see i update my post

Answer 1

Since you write @GeneratedValue you don't manage what exactly id would be.

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Provide us complete example and we'll help you

• Rodik: thank for ur reply but not the id i want to have null in the idt_parent_structure
• ADS: @Rodik I can't understand you. Could you rephrase your question?
• Rodik: Ok, I have a structure object that contains a parent object of the same type tt the time of inserting the structure object, I enter the name of this structure and If I select parent object the idt_parent_structure column in sql takes the id of the selected objet. In the second case If I don't select parent object when inserting The value of idt_parent_structure takes 0. And i want to have null not 0.