Spring boot：从一个Java实体中的两个表mysql进行简单连接

Question

我正在尝试在Spring Boot中从两个表创建一个实体：

书

+----+------+--------+-------------+
| id | name | author | releaseData |
+----+------+--------+-------------+
|  1 | bla  | bla    | 01/01/1970  |
|  2 | bla  | bla    | 01/01/1970  |
|  3 | bla  | bla    | 01/01/1970  |
|  4 | bla  | bla    | 01/01/1970  |
|    |      |        |             |
+----+------+--------+-------------+

股票

+---------+----------+--+
| book_id | quantity |  |
+---------+----------+--+
|       1 |       10 |  |
|       2 |       12 |  |
|       3 |        5 |  |
|       4 |        9 |  |
|         |          |  |
+---------+----------+--+

我想创建一个这样的图书实体：

@Entity
public class Book {

    @Id
    @GeneratedValue
    private int    id;
    private String name;
    private String author;
    private Date   releaseDate;

    @JoinTable  
    private Integer   quantity;

}

并从另一个表中获取数量的值

这可能吗？

谢谢！

Answer 1

您的实体应该是这样的：

@@ Entity公共类书籍{

@Id
@GeneratedValue
private int    id;
private String name;
private String author;
private Date   releaseDate;

@OneToMany(fetch = FetchType.EAGER)
@JoinColumn(name= "stock_book_id")
private Stock stock; }

然后，您应该像属性一样将StockDTO类添加到BookDTO中。