NHibernate HQL內部連接（SQL Server，Visual C＃）

Question

我想使用內部連接的HQL。但是，引發了查詢語法異常。

這是我的C＃代碼：

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

點這裏

• CROSS JOIN如果沒有映射關係，
• JOIN現有（映射）關係。

所以，在情況下，有沒有映射關係Question到Answer - 我們仍然可以查詢它是這樣的：

// 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"; 

在情況下，我們有映射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"; 

檢查

• 14.2. The from clause（約CROSS JOIN詳細信息）
• 14.3. Associations and joins（標準聯接相關的引用）