未在 JPA 中创建的唯一约束

Unique constraint not created in JPA(未在 JPA 中创建的唯一约束)

问题描述

我创建了以下实体 bean，并将两列指定为唯一的.现在我的问题是该表是在没有唯一约束的情况下创建的，并且日志中没有错误.有人有想法吗?

I have created the following entity bean, and specified two columns as being unique. Now my problem is that the table is created without the unique constraint, and no errors in the log. Does anyone have an idea?

@Entity
@Table(name = "cm_blockList", uniqueConstraints = @UniqueConstraint(columnNames = {"terminal", "blockType"}))
public class BlockList {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private int id;
    @ManyToOne(cascade = CascadeType.PERSIST)
    @JoinColumn(name="terminal")
    private Terminal terminal;
    @Enumerated(EnumType.STRING)
    private BlockType blockType;
    private String regEx;
}

推荐答案

好吧，我找到了另一种进行设计的方法.更多是因为设计的演变而不是解决方法.
然而，我从一位同事那里听说，他遇到了同样的问题，唯一约束仅在创建整个数据库时由休眠(我们正在运行 JBoss 4.3)创建.在现有数据库中创建新表时，它将不起作用.
所以在persistence.xml 中需要将hibernate.hbm2ddl.auto 设置为create-drop 以使其工作.不过我无法确认这一点.

Well, I found another way to make the design. More because the design evolved than a work around.
I heard however from a colleague, that had had the same problem, that unique constraint only are created by hibernate (we are running JBoss 4.3) when the entire database is created. It will not work when you create a new table in an existing database.
So in persistence.xml it is necessary to set hibernate.hbm2ddl.auto to create-drop to make it work. I can not confirm this though.

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