Java条件限制列总和低于值

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您好，我有一个关于将简单的SQL语句转换为Java休眠限制的问题.

Hi I've a question about converting a simple SQL statement into a java hibernate restriction.

SQL:

SELECT a + b FROM col WHERE a + b < 10

当我尝试将其转换为条件时，我得到:

When I try to convert this to a criteria I get:

Criteria criteria = createCriteria(); criteria.createAlias("col","col").add(Restrictions.lt("a+b",10));

但是似乎字符串"a+b"不被接受.我该如何写我的限制?

But it seems like the string "a+b" is not accepted. How do I have to write my restriction?

推荐答案

很可能是因为Hibernate试图将 a + b 解析为您实体的属性，并且您获得了

It's likely because Hibernate is trying to resolve a+b as your entity's property, and you get

org.hibernate.QueryException: could not resolve property: a+b

几乎没有解决方案:

第一个:sql限制:

//Hibernate 4.x criteria.add(Restrictions.sqlRestriction("col_a+col_b < ?", Integer.valueOf(10), org.hibernate.type.StandardBasicTypes.INTEGER); // Hibernate 3.x criteria.add(Restrictions.sqlRestriction("col_a+col_b < ?", Integer.valueOf(10), org.hibernate.Hibernate.INTEGER);

有一个问题，您必须使用列名而不是属性名.

There is one issue that you must use column names instead of property names.

第二名:公式:

使用 @Formula 注释将虚拟列添加到您的实体:

Add to your entity a virtual column using @Formula annotation:

@org.hibernate.annotations.Formula("a + b") private int aSumB;

并将其用作标准属性:

criteria.add(Restrictions.lt("aSumB", Integer.valueOf(10));

第三个自定义条件:

如果您经常使用它，请考虑通过实现 org.hibernate.criterion.Criterion

If you are using it a lot consider to create custom criteria by implementing org.hibernate.criterion.Criterion