NHibernate HQL内部连接(SQL Server,Visual C#)
我想在内部Join中使用HQL。 但是,抛出了查询语法exception。
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); }
这里的重点是
- CROSS JOIN如果没有映射关系,
- 加入现有(映射)关系。
所以,万一,没有映射关系Question
Answer
– 我们仍然可以像这样查询:
// 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";
如果我们有映射Answer.Question
和IList
// 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。 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JOIN)