You are explicitly trying to manage foreign key in DetailOrder class , which is causing the issues. let spring data jpa take care of it automatically as you are using @MappedCollection in your Order class. So you need to remove below code from your DetailOrder class.

@Column(value = "order_id") private Long orderId;

And also remove it from your constructor as well , remove this line this.orderId = orderId;

Also, i see that there is no need for having keyColumn = "id" in your @MappedCollection in your Order class , so remove it .

@MappedCollection(idColumn = "order_id") private List detailOrders;

Your updated code should be like this for DetailOrder class and Order class :

@Table(name = "products") public class DetailOrder {

@Id
private Long id;

@Column(value = "product_article")
private Long productArticle;

@Column(value = "product_name")
private String productName;

@Column(value = "product_amount")
private int productAmount;

@Column(value = "product_price")
private int productPrice;

public DetailOrder(Long id, Long productArticle, String productName, int productAmount, int productPrice) {
    this.id = id;
    this.productArticle = productArticle;
    this.productName = productName;
    this.productAmount = productAmount;
    this.productPrice = productPrice;
}

public Long getId() {
    return id;
}

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

public Long getProductArticle() {
    return productArticle;
}

public void setProductArticle(Long productArticle) {
    this.productArticle = productArticle;
}

public String getProductName() {
    return productName;
}

public void setProductName(String productName) {
    this.productName = productName;
}

public int getProductAmount() {
    return productAmount;
}

public void setProductAmount(int productAmount) {
    this.productAmount = productAmount;
}

public int getProductPrice() {
    return productPrice;
}

public void setProductPrice(int productPrice) {
    this.productPrice = productPrice;
}

}

@Table(name = "orders") public class Order {

@Id
@Column("id")
private Long id;

@Column(value = "order_number")
private String orderNumber;

@Column(value = "total_amount")
private Long totalAmount;

@Column(value = "order_date")
private Date orderDate;

@Column(value = "customer_name")
private String customerName;

@Column(value = "address")
private String deliveryAddress;

@Column(value = "payment_type")
private String paymentType;

@Column(value = "delivery_type")
private String deliveryType;

@MappedCollection(idColumn = "order_id")
private List<DetailOrder> detailOrders;


public Order(Long id, String orderNumber, Long totalAmount, Date orderDate, String customerName, String deliveryAddress, String paymentType, String deliveryType, List<DetailOrder> detailOrders) {
    this.id = id;
    this.orderNumber = orderNumber;
    this.totalAmount = totalAmount;
    this.orderDate = orderDate;
    this.customerName = customerName;
    this.deliveryAddress = deliveryAddress;
    this.paymentType = paymentType;
    this.deliveryType = deliveryType;
    this.detailOrders = detailOrders;
}

public Long getId() {
    return id;
}

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

public String getOrderNumber() {
    return orderNumber;
}

public void setOrderNumber(String orderNumber) {
    this.orderNumber = orderNumber;
}

public Long getTotalAmount() {
    return totalAmount;
}

public void setTotalAmount(Long totalAmount) {
    this.totalAmount = totalAmount;
}

public Date getOrderDate() {
    return orderDate;
}

public void setOrderDate(Date orderDate) {
    this.orderDate = orderDate;
}

public String getCustomerName() {
    return customerName;
}

public void setCustomerName(String customerName) {
    this.customerName = customerName;
}

public String getDeliveryAddress() {
    return deliveryAddress;
}

public void setDeliveryAddress(String deliveryAddress) {
    this.deliveryAddress = deliveryAddress;
}

public String getPaymentType() {
    return paymentType;
}

public void setPaymentType(String paymentType) {
    this.paymentType = paymentType;
}

public String getDeliveryType() {
    return deliveryType;
}

public void setDeliveryType(String deliveryType) {
    this.deliveryType = deliveryType;
}

public List<DetailOrder> getDetailOrders() {
    return detailOrders;
}

public void setDetailOrders(List<DetailOrder> detailOrders) {
    this.detailOrders = detailOrders;
}

}