休眠限制/条件初学者问题 [英] Hibernate Restrictions / Criteria Beginner Question

问题描述

我一直在尝试找出最好的方法来完成此任务，但无济于事.

Hi I have been trying to work out the best way to do this today to no avail.

我理想地要做的是创建一个由下面的SQL公式计算出的别名距离(尽管我对其他计算距离的方法持开放态度，但这似乎是最简单的方法)

What I would ideally like to do is to create an alias distance calculated by the SQL formula below (although I am open to other ways of calculating the distance, this was just the way that seemed it should be easiest)

一旦有了该别名，我便希望能够以一种限制"方式使用它来查找在一定距离内的所有别名.

Once I have that alias I want to be able to use it in a Restrictions fashion to find all that are within a certain distance.

我还希望能够按距离排序.

I would also like to be able to sort via distance.

这是已建立的较大搜索条件的一部分，因此，理想情况下，我希望继续使用Criteria.(我已经限制了纬度和经度值的范围，以便在较少的字段上进行距离计算.

This is part of a bigger search criteria that is built up so I would ideally like to keep using Criteria. ( I already limit the range of Lat and Long values to make the distance calculation required on less fields.

Criteria criteria = session.createCriteria(Activity.class)
       .createAlias("activityLocations", "actloc")
       .createAlias("actloc.location", "location")
       .createAlias("location.address", "addr");
       criteria.add((Restrictions.and(Restrictions.between("addr.latitude", latmin,     
       latmax),Restrictions.between("addr.longitude", truelongmin, truelongmax))));


       String sql =  "SQRT( POW( 69.1 * ( addr3_.latitude - " + point[1]     
       +" ) , 2 ) + POW( 69.1 * ( "+point[0] +" - addr3_.longitude ) * COS( addr3_.latitude /"
       +" 57.3 ) , 2 ) )  < "+distance;    
       criteria.add(Restrictions.sqlRestriction(sql));

当前我在sql查询中有addr3_，因为我正在查看详细的输出，这就是Hibernate生成查询的方式(此hack在我正在查看的一个实例中有效，但我害怕考虑更长的时间术语的含义，所以不想让它留在那里！)

Currently I have addr3_ in the sql query because I was looking at the verbose output and that is the way that Hibernate has generated the query (this hack worked in the one instance i was looking at but I dread to think about the longer term implications so would not want it to stay there!!)

推荐答案

在SQL限制中，您可以将条件根的别名称为 {alias} .要在这种情况下使用它，您需要一个以 location.address :

In SQL restrictions you can refer to the alias of the criteria root as {alias}. To use it in this case, you need a "sub criteria" rooted at location.address:

Criteria criteria = session.createCriteria(Activity.class) 
       .createAlias("activityLocations", "actloc") 
       .createAlias("actloc.location", "location");

Criteria addr = criteria.createCriteria("location.address"); 
addr.add((Restrictions.and(Restrictions.between("latitude", latmin,      
       latmax), Restrictions.between("longitude", truelongmin, truelongmax)))); 

String sql =  "SQRT( POW( 69.1 * ( {alias}.latitude - " + point[1]      
       +" ) , 2 ) + POW( 69.1 * ( "+point[0] +" - {alias}.longitude ) * COS( {alias}.latitude /" 
       +" 57.3 ) , 2 ) )  < "+distance;     
addr.add(Restrictions.sqlRestriction(sql)); 

这篇关于休眠限制/条件初学者问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！