在NHibernate Criteria查询中加入多个字段 [英] Joining on multiple fields in a NHibernate Criteria query

问题描述

我有一个 Dept 表和一个 Emp 表。

我需要以这样一种方式连接这两个表：其中子句看起来像这样：

I need to join these two table in such a way that the where clause looks something like this:

where dept.deptId = emp.DeptId and dept.deptName = emp.empTrainingName

我试过这个：

I tried this:

Criteria criteria = session.createCriteria(Dept.class).createAlias("empMap","id");

使用这个，第一个条件即 dept.deptId = emp.DeptId执行。但我不确定如何比较 dept.deptName 和 emp.empTrainingName 。

Using this, the first where condition i.e. dept.deptId = emp.DeptId is performed. But I am not sure how to compare dept.deptName with emp.empTrainingName.

我如何在NHibernate中使用Criteria API来完成这项工作？

How do I do this using the Criteria API in NHibernate?

推荐答案

Criteria criteria = session.createCriteria(Dept.class, "department")
                           .createAlias("empMap", "employee")
                           .add(Restrictions.eqProperty("department.deptName", 
                                                        "employee.empTrainingName"));

您也可以使用with子句，这在左连接的情况下是必需的：

You may also use a with clause, which would be necessary in case of a left join:

Criteria criteria = 
    session.createCriteria(Dept.class, "department")
           .createAlias("empMap", 
                        "employee", 
                        Criteria.LEFT_JOIN,
                        Restrictions.eqProperty("department.deptName", 
                                                "employee.empTrainingName"));

注意：您的名字选择很糟糕。而不是 Dept.deptId ，为什么不使用 Department.id ？而不是 Emp.empTrainingName ，为什么不选择 Employee.trainingName ？

Side note: your choices of names are awful. Instead of Dept.deptId, Why not use Department.id? Instead of Emp.empTrainingName, why not choose Employee.trainingName?

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