hibernate - createCriteria或createAlias? [英] hibernate - createCriteria or createAlias?
问题描述
如果我想搜索那些接受数学和约翰课程的学生是他的小组:
我应该使用createCriteria或createAlias?
条件:
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与初始条件结合在一起?
别名:
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和createAlias?我认为这种情况是一样的...
CreateAlias和CreateCriteria在当前相同 Hibernate和NHibernate的版本。唯一的区别是,CreateCriteria有两个额外的重载没有别名参数。
假设它们在旧版本中有所不同,但任何差异都早已消失。
别名可以用另一个别名来定义,所以你的第一个例子可以写成:
// 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 ));
If I want to search those students who take class "Math" and "John" is his group:
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"));
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"));
When to use createCriteria and when createAlias? I think the boath are the same...
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.
Presumably they were different in a older version, but any differences are long gone.
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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