@Column(unique = true)

[shizuka]

@Entity(name = "USERS")
public class User {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
private int id;

@Column(unique = true, nullable = false, name = "login")
private String login;

@Column(nullable = false, name = "name")
private String name;

@Column(nullable = false, name = "sur_name")
private String surName;

@Column(nullable = false, length = 32, name = "password")
@Size(max = 32, min = 32)
private String password;

@Enumerated(EnumType.STRING)
@Column(name = "position", nullable = false)
private Position position = Position.CUSTOMER;

@Column(nullable = false, name = "email")
private String email;

@Column(name = "salary", nullable = false)
private double salary = 0.0;

@Size(min = 0, max = 100)
@Column(name = "prepayment")
private short prepayment = 100;

@OneToMany(mappedBy = "user")
private List<Order> orders;

public User() {
}

public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getSurName() {
    return surName;
}

public void setSurName(String surName) {
    this.surName = surName;
}

public String getPassword() {
    return password;
}

public void setPassword(String password) {
    this.password = password;
}

public Position getPosition() {
    return position;
}

public void setPosition(Position position) {
    this.position = position;
}

public String getEmail() {
    return email;
}

public void setEmail(String email) {
    this.email = email;
}

public double getSalary() {
    return salary;
}

public void setSalary(double salary) {
    this.salary = salary;
}

public short getPrepayment() {
    return prepayment;
}

public void setPrepayment(short prepayment) {
    this.prepayment = prepayment;
}

public List<Order> getOrders() {
    return orders;
}

public void setOrders(List<Order> orders) {
    this.orders = orders;
}

public String getLogin() {
    return login;
}

public void setLogin(String login) {
    this.login = login;
}

♪

Code execution

public static void main(String[] args) {
ApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");
UserDao ud = (UserDao)ctx.getBean("userDaoImpl");
User u = new User();
u.setName("Alex");
u.setLogin("mooks");
u.setSurName("Pdln");
u.setEmail("a@mail.com");
u.setPassword("password");
u.setPosition(Position.CUSTOMER);
ud.addUser(u);
u = new User();
u.setName("Alex");
u.setLogin("mooks");
u.setSurName("Pdln");
u.setEmail("a@mail.com");
u.setPassword("password");
u.setPosition(Position.CUSTOMER);
ud.addUser(u);

}

Everyone on the bd record two identical records.
What's the problem?

Used Spring + JPA(EclipseLink)

[obi]

If you didn't set up a table with JPA, you need to manually create a unique line. Further details https://stackoverflow.com/a/3498242/2546083 and https://stackoverflow.com/q/15372654/2546083