sql查询的HQl查询？

Question

以下是一个SQL查询，我希望hql查询相同??任何建议，将不胜感激。

在这个查询中，我试图抓取两张表'blogs'和'askquestions'的记录，这些记录没有与eachother映射。

SELECT blog_title as title ,created_date as date FROM blog UNION SELECT ask_question as title , created_on as date FROM askquestions) as aa ORDER BY date DESC 

Answer 1

不幸HQL不支持UNION，UNION ALL作为尚未。

你仍然可以尝试以下解决办法：

// Create two query strings for two sub HQLs 
String firstHQLQueryStr = " from blog b where <criteria1>"; 
String secondHQLQueryStr = "from askquestions a where <criteria2>"; 

// Divide the two select clauses into two sub HQLs 
Query query1 = session.createQuery(firstHQLQueryStr); 
Query query2 = session.createQuery(secondHQLQueryStr); 

// Fetch the data from database using these two sub HQLs first 
List firstDataList= query1.list(); 
List secondDataList= query2.list(); 

//Combine the results 
firstDataList.add(secondDataList); 

// Collection equivalent to UNION ALL 
List nonUniqueCollection = firstDataList; 

//Collection equivalent to Union (as non-unique elements are removed) 
HashSet uniqueCollection = new HashSet(nonUniqueCollection); 

希望有所帮助。

Answer 2

尝试像这样...

select * from ((blog_title as title ,created_date as date FROM blog) union (SELECT ask_question as title , created_on as date FROM askquestions)) as a order by a.date desc;