休眠 - createCriteria 或 createAlias? [英] hibernate - createCriteria or createAlias?

问题描述

如果我要搜索那些上过Math"和John"课的学生:

If I want to search those students who take class "Math" and "John" is his group:

我应该使用 createCriteria 还是 createAlias?

shoud I use createCriteria or createAlias?

Criteria:

Criteria criteria = session.createCriteria(Student.class);
Criteria subquery1 = criteria.createCriteria("courses", course).add(Restrictions.eq(course.name, "Math"));
Criteria subquery2 = criteria.createCriteria("group", student).add(Restrictions.eq(student.name, "John"));

如何将 subquery1 和 subquery2 与初始条件放在一起?

how to put subquery1 and subquery2 together with initial criteria?

Alias:

Criteria criteria = session.createCriteria(Student.class).
createAlias("courses", course).add(Restrictions.eq(course.name, "Math")).
createCriteria("group", student).add(Restrictions.eq(student.name, "John"));

何时使用 createCriteria，何时使用 createAlias?我认为船是一样的...

When to use createCriteria and when createAlias? I think the boath are the same...

推荐答案

CreateAlias 和 CreateCriteria 在当前版本的 Hibernate 和 NHibernate 中相同.唯一的区别是 CreateCriteria 有 2 个没有别名参数的额外重载.

CreateAlias and CreateCriteria are identical in the current versions of Hibernate and NHibernate. The only difference being that CreateCriteria has 2 additional overloads without the alias parameter.

据推测，它们在旧版本中有所不同，但任何差异早已不复存在.

Presumably they were different in a older version, but any differences are long gone.

一个别名可以根据另一个别名来定义，所以你的第一个例子可以写成:

An alias can be defined in terms of another alias, so your first example can be written as:

// Java
Criteria criteria = session.createCriteria(Student.class)
    .createAlias("courses", "course")
    .createAlias("course.group", "student")
    .add(Restrictions.eq("course.name", "Math"))
    .add(Restrictions.eq("student.name", "John"));

// C#
ICriteria criteria = session.CreateCriteria<Student>()
    .CreateAlias("Courses", "course")
    .CreateAlias("course.Group", "student")
    .Add(Restrictions.Eq("course.Name", "Math"))
    .Add(Restrictions.Eq("student.Name", "John"));

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