Nhibernate Criteria Group By clause and select other data that is not grouped

Posted by Peter R on Stack Overflow See other posts from Stack Overflow or by Peter R
Published on 2010-05-25T18:55:02Z Indexed on 2010/05/25 19:01 UTC
Read the original article Hit count: 606

Filed under:

nhibernate

|

criteria

Hi,

I have a parent child relationship, let's say class and children. Each child belongs to a class and has a grade. I need to select the children (or the ids of the children) with the lowest grade per class.

session.CreateCriteria(typeof(Classs))
 .CreateAlias("Children", "children")
 .SetProjection(Projections.ProjectionList()
     .Add(Projections.Min("children.Grade"))
     .Add(Projections.GroupProperty("Id"))
 )
 .List<Object[]>();

This query returns me the lowest grade per class, but I don't know which child got the grade. When I add the children's Id to the group, the group is wrong and every child gets returned.

I was hoping we could just select get the id's of those childs without grouping them. If this is not possible, then maybe there is a way to solve this with subqueries?

© Stack Overflow or respective owner

Related posts about nhibernate

How can I eager-load a child collection mapped to a non-primary key in NHibernate 2.1.2?

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I have two objects with a many-to-many relationship between them, as follows: public class LeftHandSide { public LeftHandSide() { Name = String.Empty; Rights = new HashSet<RightHandSide>(); } public int Id { get; set; } public string Name { get; set;… >>> More
Nhibernate 2.1 and mysql 5 - InvalidCastException on Setup

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello there, I am trying to use NHibernate with Spring.Net und mySQL 5. However, when setting up the connection and creating the SessionFactoryObject, I get this InvalidCastException: NHibernate seems to cast MySql.Data.MySqlClient.MySqlConnection to System.Data.Common.DbConnection which causes… >>> More
Nhibernate transactions:Avoiding Nhibernate dependency in the service layer

as seen on Stack Overflow - Search for 'Stack Overflow'
One of practices advocated by Nhibernate experts is to do all actions in inside a transaction. In a typical 3 tier web architecture, Nhibernate depedency is limited the data layer. In such a case is it fine to use using (var tr = NHibernateSession.Current.BeginTransaction()) { at the controller… >>> More
Series of abstract classes and NHibernate

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello, and first off thanks for your time to look at this. For a research project I'm working on, I have a somewhat complex design (which I've been given) to persist to a database via NHibernate. Here's an example of the class hierarchy: TransitStrategy, TransportationCompany and TransportationLocation… >>> More
Using Time columns with NHibernate, Fluent NHibernate and SQL Server 2008

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello, I have a table with a time column in my SQL Server 2008 database. The property of the object I'm trying to map to is a TimeSpan. How can i tell FluentNHibernate to use the TimeAsTimeSpan NHibernate type, so that I don't have cast problems? >>> More

Related posts about criteria

Hibernate Criteria: Add restrictions to Criteria and DetachedCriteria

as seen on Stack Overflow - Search for 'Stack Overflow'
Currently our queries add a variety of Restrictions to ensure the results are considered active or live. These Restrictions are used in several places/queries so a method was setup similar to public Criteria addStandardCriteria(Criteria criteria, ...) { // Add restrictions, create aliases… >>> More
Criteria SpatialRestrictions.IsWithinDistance NHibernate.Spatial

as seen on Stack Overflow - Search for 'Stack Overflow'
Has anyone implemented this, or know if it would be difficult to implement this/have any pointers? public static SpatialRelationCriterion IsWithinDistance(string propertyName, object anotherGeometry, double distance) { // TODO: Implement throw new NotImplementedException(); } from NHibernate… >>> More
Hibernate Criteria query on association

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi There, How would I go about executing the following Hibernate query using the criteria API. I have an object Parent with List children. I would like to search through all parents and find which parents contain a specified child. i.e. List findParent(Child child); Thanks. >>> More
Delete all rows that do not have the value: Criteria 1 or Criteria 2 or Criteria 3 in Column D --> Using VBA Macro for excel

as seen on Stack Overflow - Search for 'Stack Overflow'
I am new to Macro's/VBA and cannot seem to figure out how to do this action for multiple criteria. I am trying to Delete all rows that do not have the value: Identify Fail or Identify Success in Column D. I write the following code and it works for one criteria "Identify Fail": '***********************************************' Sub… >>> More
More than one location provider at same time

as seen on Stack Overflow - Search for 'Stack Overflow'
I have some problems with location systems. I have a service that implements locationlistener. I want to get the best location using network when possible, gps if network is not enough accurate (accuracy greater than 300mt). The problem is this. I need location (accurate if possible, inaccuarte otherways)… >>> More