休眠检查注解 [英] Hibernate Check Annotation

问题描述

我有一个包含三个字段的表，例如a，b，c.我想添加一个约束，以确保如果a不为null，则b和c也不为null.我已经使用下面的SQL完成了

I have a table with three fields, say a, b, c. I would like to add a constraint ensuring that if a is not null, then also b and c are not null. I have done that using following SQL

ALTER TABLE sample 
ADD CONSTRAINT no_nulls
CHECK (CASE WHEN a IS NOT NULL THEN b IS NOT NULL AND c IS NOT NULL END)

有没有一种方法可以使用休眠注释@Check来达到相同的效果?

Is there a way to achieve same effect using hibernate annotation @Check?

我找不到带有该注释的有用示例，开发人员是否倾向于完全不使用它?

I can't find a helpful example with that annotation, do developers tend not to use it at all?

推荐答案

是的，如果在类级别使用@Check是可能的，如下所示:

Yes it is possible if @Check is used at class level like this:

@Entity
@Check(constraints = "COL_A IS NULL OR (COL_B IS NOT NULL and COL_C IS NOT NULL)")
public class Sample {

    @Column(name = "COL_A")
    private Long a;

    @Column(name = "COL_B")
    private Long b;

    @Column(name = "COL_C")
    private Long c;

}

(请注意，我使用@jarlh注释重写了您的条件.). @Check批注的constraints子句需要引用@Column的name属性(它必须是纯SQL).

(Note that I rewrote your condition using @jarlh comment.). The constraints clause of @Check annotation needs to refer to the name attribute of @Column (it must be pure SQL).

@Check注释必须处于类级别.

@Check annotation needs to be at class level because of a Hibernate bug.

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