NHibernate HQL内部连接（SQL Server，Visual C＃） [英] NHibernate HQL Inner Join (SQL Server,Visual C#)

问题描述

我想用inner join来使用HQL。但是，引发了查询语法异常。

这是我的C＃代码：

  string sqlQuery =Select fq FROM Answers as fq INNER JOIN Questions as q+ 
on fq.questionId = q.questionId; 
 
 IList结果; 
 int count = 0; 
 
尝试
 {
 using（ISession session = ConnectionModule.OpenSession（））
 {
 IQuery query = session.CreateQuery（sqlQuery）; 
 session.CreateCriteria（typeof（Answers））; 
 Result = query.List（）; 
 
 $ b $ catch（Exception ex）
 {
 MessageBox.Show（ex.Message +\\\
+ ex.InnerException）; 
 
 $ / code $ / pre 
 
解决方案
如果没有映射关系，
 
 
 
 
 CROSS JOIN 
 
 
加入现有（映射）关系。 li> 
 
 
 
 
因此，如果没有映射关系问题到<$ c $ 
  // //代替INNER JOIN我们可以这样查询：使用'逗号'来产生CROSS JOIN 
 //而不是ON我们需要WHERE 
 // string sqlQuery =Select fq FROM Answers as fq，INNER JOIN Questions as q+ 
 // on fq.questionId = q.questionId; 
 
 string sqlQuery =Select fq FROM Answers as fq，Questions as q+ 
WHERE fq.questionId = q.questionId; 
  
如果我们映射 Answer.Question 和 IList< Answer>问题.Answers  
  //参考（C＃）是如何表达ON 
 string sqlQuery =Select fq FROM Answers as fq INNER JOIN fq.Questions as q; 
  
检查 
 
 
 
 
  14.2。 from子句 （有关CROSS JOIN的详细信息） 
 
 
  14.3。关联和连接 （与引用相关的标准连接） 
 
 
 
I want to using HQL with inner Join. But, a query syntax exception is thrown.

This is my C# code:
string sqlQuery = "Select fq FROM Answers as fq INNER JOIN Questions as q " +
    " on fq.questionId=q.questionId";

IList Result;
int count = 0;

try
{
    using (ISession session = ConnectionModule.OpenSession())
    {
        IQuery query = session.CreateQuery(sqlQuery);
        session.CreateCriteria(typeof(Answers));
        Result = query.List();
    }
}
catch(Exception ex) 
{
    MessageBox.Show(ex.Message+"\n"+ex.InnerException);
}

解决方案
The point here is


CROSS JOIN if there are no mapped relations,
JOIN on existing (mapped) relations.


So, in case, there is no mapped relation Question to Answer - we still can query it like this:
// instead of INNER JOIN we use 'comma' to produce CROSS JOIN
// instead of ON we need WHERE
// string sqlQuery = "Select fq FROM Answers as fq, INNER JOIN Questions as q "+ 
//  "on fq.questionId=q.questionId";

string sqlQuery = "Select fq FROM Answers as fq, Questions as q " +
    " WHERE fq.questionId=q.questionId";
In case we have mapping Answer.Question and IList<Answer> Question.Answers 
// the Reference (C#) is the way how to express ON
string sqlQuery = "Select fq FROM Answers as fq INNER JOIN fq.Questions as q";
Check the


14.2. The from clause (details about CROSS JOIN)
14.3. Associations and joins (standard JOIN related to references)


                        
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