How can I write this query with QueryOver.
select * from User usr where exists (select ord.ID from Order ord where ord.UserID = usr.ID)
I know we can write subqueries with QueryOver like ..WithSubSelect.WhereProperty(x=>x.ID == subquery.as<int>()). But I want to use field of the main query in the subquery in order to use it in where clause.
Is this possible ?
thank you for your helps
User userAlias = null;
var subquery = QueryOver.Of<Order>()
.Where(o => o.User == userAlias)
// or
.Where(o => o.User.Id == userAlias.Id)
var usersWithOrders = session.QueryOver(() => userAlias)
.WithSubqueries.WhereExists(subquery)
.List();
Related
I'm accustomed to GroupBy() being more of an art than a science, but maybe someone can help me with a very specific problem:
Given the following code
var results = session.Query<MyClass>()
.GroupBy(c => c.OtherPersistentObject)
.Select(group => new
{
key = group.Key,
count = group.Count()
})
.ToList();
The generated query comes out like this:
/* [expression] */select
otherclass_.ID as col_0_0_,
cast(count(*) as INT) as col_1_0_,
otherclass_.ID as id1_1_,
otherclass_.START_DATE as start2_1_,
otherclass_.END_DATE as end3_1_,
otherclass_.Zone as zone9_1_
from
mytable mytable0_
left outer join
otherclass otherclass_
on mytable0_.otherID=otherclass_.ID
group by
mytable0_.otherID
which gives me the SQL error "Column 'otherclass .ID' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause"
Is there a way to get the Select to do what I want?
TIA
It's a known NHibernate issue NH-3027.
As a workaround you can use last approach described in this answer (rewrite GroupBy part as sub-query). So your query can be rewritten to something like:
var results = session.Query<MyClass>()
.Where(c => c == session.Query<MyClass>().First(cs => cs.OtherPersistentObject == c.OtherPersistentObject))
.Select(x => new
{
key = x.OtherPersistentObject,
count = session.Query<MyClass>().Count(cs => cs.OtherPersistentObject == x.OtherPersistentObject)
}).ToList();
Try this:
var results = session
.Query<MyClass>()
.GroupBy(c => c.OtherPersistentObject)
.Select(group => new
{
key = group.Key.Id,
count = group.Count()
})
.ToList();
Here you can find the reason for the error.
I need help converting this sql query into QueryOver Nhibernate criteria.
select distinct * from event e where e.name like '%req%'
or e.Id in (select r.eventId from requirement r where r.name like '%req%')
or e.Id in (select r.eventId from requirement r where r.id
in (select s.requirementId from solution s where s.name like '%sol%'))
var queryOver = session.QueryOver<Event>()
.Where(x => x.Name.IsInsensitiveLike("%"+searchTerms[1]+"%"))
.OrderBy(x => x.CreatedOn).Asc;
So far I have the main query but couldn't find enough reference material on how to add the subqueries. Haven't been successful using joinQueryOver.
Event has one-to-many rel with requirement and requirement has one-to-many rel with solution.
Requirement reqAlias = null;
Solution solAlias = null;
var subQuery = QueryOver.Of<Event>()
.JoinAlias(x => x.Requirements, () => reqAlias)
.Where(x => x.Name.IsInsensitiveLike(searchTerms[2]))
.JoinAlias(() => reqAlias.Solutions, () => solAlias)
.Where(x => x.Name.IsInsensitiveLike(searchTerms[3]))
.Select(Projections.Group<Event>(x => x.Id));
var events = session.QueryOver<Event>()
.Where(x => x.Name.IsInsensitiveLike(searchTerms[1]))
.WithSubquery.WhereProperty(x => x.Id).In(subQuery)
.List().ToList();
still not working.
When you use IsInsensitiveLike NHibernate appends the % after parsing, and uses lower to do a lower case comparison. In your code, you are appending the % yourself, which results in,
select distinct * from event e where e.name like %lower('%req%')%
which in turn, doesn't work.
Also, you have 3 subqueries, no a big one, so you need to restructure your code to account for that:
select r.eventId from requirement r where r.name like '%req%'
to
var firstQuery = QueryOver.Of<Requirement>()
.Where(r => r.Name.IsInsensitiveLike(searchTerms[2]))
.Select(r => r.EventId);
then,
select s.requirementId from solution s where s.name like '%sol%'
to
var solutionQuery = QueryOver.Of<Solution>()
.Where(s => s.Name.IsInsensitiveLike(searchTerms[3]));
then,
select r.eventId from requirement r where r.id
in (select s.requirementId from solution s where s.name like '%sol%')
to
var requirementQuery = QueryOver.Of<Requirement>()
.WithSubquery
.WhereProperty(r => r.Id).In(solutionQuery)
.Select(r => r.EventId);
Then you need to construct the main query using Restrictions.Or to include the 3 queries.
I am having issues getting Nhibernate 3.3.2.4000 to generate the correct subquery used in the orderby clause as displayed below:
select *
from dbo.Person p inner join dbo.Task t on p.Task_FK = p.TaskId
order by (select p.CustomerNumber where p.IsMain=1) desc
We have two entities: Task and Person
One task can have N persons related to it. I.e Task has an IList property.
How can I make Nhibernate generate the correct subquery ? I have gotten as far as something like this with the Query API:
query = query.OrderBy(x => x.Persons.Single(t => t.CustomerNumber));
but I am unsure how I can correctly generate the where clause as displayed in the original sql query. Is this perhaps easier done using the queryover api somehow?
Any advice or guidance is most welcome.
Task task = null
Person person = null;
var subquery = QueryOver.Of<Task>()
.Where(t => t.Id == task.Id)
.JoinQueryOver(t => t.Persons, () => person)
.Where(p => p.IsMain)
.Select(() => person.CustomerNumber);
var query = session.QueryOver(() => task)
.OrderBy(Projections.SubQuery(subquery))
.FetchMany(x => x.Persons)
return query.List();
Basically I crossed the same problem of Linq provider in this linq-to-nhibernate-produces-unnecessary-joins
List<Competitions> dtoCompetitions;
dtoCompetitions = (from compset in session.Query<FWBCompetitionSet>()
where compset.HeadLine == true
&& compset.A.B.CurrentSeason == true
select (new Competitions
{
CompetitionSetID = compset.CompetitionSetID,
Name = compset.Name,
Description = compset.Description,
Area = compset.Area,
Type = compset.Type,
CurrentSeason = compset.A.B.CurrentSeason,
StartDate = compset.StartDate
}
)).ToList();
Which leads to duplicated join in its generated SQL
SELECT fwbcompeti0_.competitionsetid AS col_0_0_,
fwbcompeti0_.name AS col_1_0_,
fwbcompeti0_.DESCRIPTION AS col_2_0_,
fwbcompeti0_.area AS col_3_0_,
fwbcompeti0_.TYPE AS col_4_0_,
fwbseason3_.currentseason AS col_5_0_,
fwbcompeti0_.startdate AS col_6_0_
FROM fwbcompetitionset fwbcompeti0_
INNER JOIN A fwbcompeti1_
ON fwbcompeti0_.competitionseasonid = fwbcompeti1_.competitionseasonid
INNER JOIN A fwbcompeti2_
ON fwbcompeti0_.competitionseasonid = fwbcompeti2_.competitionseasonid
INNER JOIN B fwbseason3_
ON fwbcompeti2_.seasonid = fwbseason3_.seasonid
WHERE fwbcompeti0_.headline = #p0
AND fwbseason3_.currentseason = #p1
Notice these joins, which are totally duplicated and also affect my SQL Server's performence.
INNER JOIN A fwbcompeti1_
ON fwbcompeti0_.competitionseasonid = fwbcompeti1_.competitionseasonid
INNER JOIN A fwbcompeti2_
ON fwbcompeti0_.competitionseasonid = fwbcompeti2_.competitionseasonid
Update1
In the NHibernate 3.2, this LiNQ bug is still valid, and I could not find a simple and reasonable Linq solution.
So I used QueryOver + JoinAlias + TransformUsing finishing the job, workds perfect to me.
FWBCompetitionSet compset = null;
FWBCompetitionSeason compseason = null;
FWBSeason season = null;
IList<Competitions> dtoCompetitions;
dtoCompetitions = session.QueryOver<FWBCompetitionSet>(() => compset)
.JoinAlias(() => compset.FWBCompetitionSeason, () => compseason)
.JoinAlias(() => compseason.FWBSeason, () => season)
.Where(() => compset.HeadLine == true)
.And(() => season.CurrentSeason == true)
.SelectList(
list => list
.Select(c => c.CompetitionSetID).WithAlias(() => compset.CompetitionSetID)
.Select(c => c.Name).WithAlias(() => compset.Name)
.Select(c => c.Description).WithAlias(() => compset.Description)
.Select(c => c.Area).WithAlias(() => compset.Area)
.Select(c => c.Type).WithAlias(() => compset.Type)
.Select(c => season.CurrentSeason).WithAlias(() => season.CurrentSeason)
.Select(c => c.StartDate).WithAlias(() => compset.StartDate)
)
.TransformUsing(Transformers.AliasToBean<Competitions>())
.List<Competitions>();
Yet Another Edit:
I think I finally found out what's going on. It seems that the LINQ to NHibernate provider has trouble navigating associations from the target to the source table and generates a separate join each time it encounters such an association.
Since you don't provide your mapping, I used the mapping from linq-to-nhibernate-produces-unnecessary-joins. This model has a Document with one Job and many TranslationUnits. Each TranslationUnit has many Translation entities.
When you try to find a Translation based on a Job, you are traversing the associations in the reverse order and the LINQ provider generates multiple joins: one for Translation -> TranslationUnit and one for TranslationUnit to Document.
This query will generate redundant joins:
session.Query<TmTranslation>()
.Where(x => x.TranslationUnit.Document.Job == job)
.OrderBy(x => x.Id)
.ToList();
If you reverse the navigation order to Document -> TranslationUnit -> Translation, you get a query that doesn't produce any redundant joins:
var items=(from doc in session.Query<Document>()
from tu in doc.TranslationUnits
from translation in tu.Translations
where doc.Job ==job
orderby translation.Id
select translation).ToList();
Given this quirkiness, QueryOver seems like a better option.
Previous Edit:
I suspect the culprit is compset.A.B.CurrentSeason. The first joined table (fwbcompeti1_) returns A.B while the next two (fwbcompeti2_ and fwbseason3_) are used to return A.B. The LINQ to NHibernate provider doesn't seem to guess that A is not used anywhere else and fails to remove it from the generated statement.
Try to help the optimizer a little by replacing CurrentSeason = compset.A.B.CurrentSeason with CurrentSeason = true from the select, since your where statement returns only items with CurrentSeason == true.
EDIT: What I mean is to change the query like this:
List<Competitions> dtoCompetitions;
dtoCompetitions = (from compset in session.Query<FWBCompetitionSet>()
where compset.HeadLine == true
&& compset.A.B.CurrentSeason == true
select (new Competitions
{
CompetitionSetID = compset.CompetitionSetID,
Name = compset.Name,
Description = compset.Description,
Area = compset.Area,
Type = compset.Type,
CurrentSeason = true,
StartDate = compset.StartDate
}
)).ToList();
I simply replace the value compset.A.B.CurrentSeason with true
I am trying to use query over to retrieve a collection of entities based upon a join/subquery as per the example below:
var types = new List<ActivityType>{ActivityType.CommentMedia, ActivityType.KeepMedia};
return _sessionFactory.GetCurrentSession()
.QueryOver<Activity>()
.Where(a.Type.IsIn(types))
.WithSubquery.WhereExists(QueryOver.Of<Resource>()
.Where(k => k.MemberKey == userId)
.Where(k => k.ResourceKey == activity.ResourceId)
)
.Take(take)
.List();
In other words retrieve all activities which are in the resource table matching the user and resource id.
I would do this in raw sql by either joining to Resource, or a subquery:
where a.ResourceId in (select resourceKey from resource where resource.memberkey = a.MemberId)
Not sure how to proceed in nhibernate though. Any suggestions?
(We don't want to use a mapping, as we want to keep the Activity entity very simple for performance reasons)
Thanks in advance
Activity activity = null;
return _sessionFactory.GetCurrentSession()
.QueryOver(() => activity)
.Where(a.Type.IsIn(types))
.WithSubquery.WhereProperty(a => a.ResourceId).In(QueryOver.Of<Resource>()
.Where(k => k.MemberKey == userId)
.Where(k => k.ResourceKey == activity.ResourceId)
)
.Take(take)
.List();