Question

我有一个NHibernate Linq查询，我需要将其翻译为HQL：

var result = Conexion.Session.Query<Person>();
result = result.Where(p => p.addresses.Any(a => a.City.Name == "mycity"));

返回在城市中至少拥有一个地址的人员＃34; MyCity＆＃34;

我如何翻译＆＃34;任何＆＃34;条款为＆＃34; HQL sintax＆＃34;？

感谢。

Answer 1

这是等效的HQL：

select p 
from Person p
join p.addresses a
join a.city c
where c.name = :cityName

任何只需通过一对多联接来解决。

如果同一城市内有多个地址，要删除Person实体重复项，您需要使用distinct：

select distinct p 
from Person p
join p.addresses a
join a.city c
where c.name = :cityName

或

select distinct p 
from Address a 
join fetch a.person p 
join a.city c 
where c.name = :cityName

Answer 2

复制由以下内容生成的SQL：

var result = Conexion.Session.Query<Person>();
result = result.Where(p => p.addresses.Any(a => a.City.Name == "mycity"));

我们必须这样做：

var hql = "SELECT p FROM Person p WHERE EXISTS "
          + "(SELECT a FROM Address a "
          + "  LEFT JOIN a.City c "
          + "  WHERE p = a.Person " 
          + "    AND c.Name = 'mycity') ";

mycity 可以是参数：

var hql = "SELECT p FROM Person p WHERE EXISTS "
          + "(SELECT a FROM Address a "
          + "  LEFT JOIN a.City c "
          + "  WHERE p = a.Person " 
          + "    AND c.Name = :mycity) ";

var result = Conexion.Session.CreateQuery(hql)
        .SetParameter("mycity", "...")
        .List<Person()

如果Address有Person的后引用，那将是有效的，因为这是条件的一部分 WHERE p = a.Person

如果该映射只包含从Person到Address的方式，那么hql必须是这样的：

var hql = "SELECT p FROM Person p WHERE EXISTS "
          + "(SELECT p2 FROM Person p2 "
          + "  LEFT JOIN p2.addresses a "
          + "  LEFT JOIN a.City c "
          + "  WHERE p = p2 " 
          + "    AND c.Name = :mycity) ";

即使地址与人之间的参考缺失，这也会有效

Linq＆＃34; .any＆＃34; HQL中的等价物

2 个答案: