对于这种情况，如何在休眠中定义唯一约束？

发布于 2025-01-08 08:51:20 字数 674 浏览 1 评论 0原文

数据库级别的 Destination 和 DestinationAlias 如下所示：

DestinationAlias and Destination

在 DestinationAlias 中，(idDestination, alias) 是唯一的。

DestinationAlias 的 POJO：

@Entity
@Table(name = "DESTINATIONALIAS",
uniqueConstraints = { @UniqueConstraint(columnNames={"IDDESTINATION", "ALIAS"}) }
        )
public final class DestinationAlias {

// ..

    @ManyToOne(fetch=FetchType.LAZY, cascade={CascadeType.ALL})
    @JoinColumn(name="IDDESTINATION", nullable=false)
    public Destination getMainCity() {
        return mainCity;
    }
}

唯一约束应该是 IDDESTINATION 还是“MAINCITY”？

原文

Destination and DestinationAlias at database level look like this:

DestinationAlias and Destination

In DestinationAlias, (idDestination, alias) is unique.

POJO for DestinationAlias:

@Entity
@Table(name = "DESTINATIONALIAS",
uniqueConstraints = { @UniqueConstraint(columnNames={"IDDESTINATION", "ALIAS"}) }
        )
public final class DestinationAlias {

// ..

    @ManyToOne(fetch=FetchType.LAZY, cascade={CascadeType.ALL})
    @JoinColumn(name="IDDESTINATION", nullable=false)
    public Destination getMainCity() {
        return mainCity;
    }
}

Should the unique constraint be IDDESTINATION or "MAINCITY" ?

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新雨望断虹 2025-01-15 08:51:20

唯一约束注释需要一个列名列表。所以就你而言，不，它不应该是“MAINCITY”。另请注意，最佳实践是使用与实际数据库字段相同的大小写，因为某些数据库区分大小写。所以你的代码应该是：

@Entity
@Table(name = "DestinationAlias", uniqueConstraints = { @UniqueConstraint(columnNames = {
        "idDestination", "alias" }) })
public final class DestinationAlias {
    // ....
}

请参阅： http://docs.oracle .com/javaee/6/api/javax/persistence/UniqueConstraint.html

The unique constraint annotation expects a list of column names. So in your case, no, it should not be 'MAINCITY'. Also note thats its best practice to use the same case as your actual database fields, as some databases are case sensitive. So your code should be:

@Entity
@Table(name = "DestinationAlias", uniqueConstraints = { @UniqueConstraint(columnNames = {
        "idDestination", "alias" }) })
public final class DestinationAlias {
    // ....
}

See: http://docs.oracle.com/javaee/6/api/javax/persistence/UniqueConstraint.html

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