NHibernate HQL内部连接（SQL Server，Visual C＃）

Question

我想使用内部连接的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 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); 
} 

Answer 1

点这里

• CROSS JOIN如果没有映射关系，
• JOIN现有（映射）关系。

所以，在情况下，有没有映射关系Question到Answer - 我们仍然可以查询它是这样的：

// 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"; 

在情况下，我们有映射Answer.Question和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"; 

检查

• 14.2. The from clause（约CROSS JOIN详细信息）
• 14.3. Associations and joins（标准联接相关的引用）