We are trying to upgrade to NHibernate 3.0 and now i am having problem with the following Linq query. It returns "Only one expression can be specified in the select list when the subquery is not introduced with EXISTS." error.
This is the linq query in the controller.
var list = (from item in ItemTasks.FindTabbedOrDefault(tab)
select new ItemSummary
{
Id = item.Id,
LastModifyDate = item.LastModifyDate,
Tags = (from tag in item.Tags
select new TagSummary
{
ItemsCount = tag.Items.Count,
Name = tag.Name
}).ToList(),
Title = item.Title
});
and the following is the sql generated for this query
select TOP ( 1 /* #p0 */ ) item0_.Id as col_0_0_,
item0_.LastModifyDate as col_1_0_,
(select (select cast(count(* ) as INT)
from dbo.ItemsToTags items3_,
dbo.Item item4_
where tag2_.Id = items3_.Tag_id
and items3_.Item_id = item4_.Id),
tag2_.Name
from dbo.ItemsToTags tags1_,
dbo.Tag tag2_
where item0_.Id = tags1_.Item_id
and tags1_.Tag_id = tag2_.Id) as col_2_0_,
item0_.Title as col_3_0_ from dbo.Item item0_ order by item0_.ItemPostDate desc
ps:If i remove the Tags property in the linq query, it works fine.
Where is the problem in the query?
Thanks in advance.
I've got the same Generic ADO Exception error, I think it's actually the limitation of SQL server;
Is it possible somehow load object graph with projections in collections?
If I try this one:
var cats = q.Select(t => new cat()
{
NickName = t.NickName,
Legs = t.Legs.Select(l => new Leg()
{
Color = l.Color,
Size = l.Size
}).ToList()
}).ToList();
That does the same error..
Related
I have a situation where two tables should be joined with multiple columns with or condition. Here, I have a sample of sql query but i was not able to convert it into linq query.
select cm.* from Customer cm
inner join #temp tmp
on cm.CustomerCode = tmp.NewNLKNo or cm.OldAcNo = tmp.OldNLKNo
This is how i have write linq query
await (from cm in Context.CustomerMaster
join li in list.PortalCustomerDetailViewModel
on new { OldNLKNo = cm.OldAcNo, NewNLKNo = cm.CustomerCode } equals new { OldNLKNo = li.OldNLKNo, NewNLKNo = li.NewNLKNo }
select new CustomerInfoViewModel
{
CustomerId = cm.Id,
CustomerCode = cm.CustomerCode,
CustomerFullName = cm.CustomerFullName,
OldCustomerCode = cm.OldCustomerCode,
IsCorporateCustomer = cm.IsCorporateCustomer
}).ToListAsync();
But this query doesn't returns as expected. How do I convert this sql query into linq.
Thank you
You didn't tell if list.PortalCustomerDetailViewModel is some information in the database, or in your local process. It seems that this is in your local process, your query will have to transfer it to the database (maybe that is why it is Tmp in your SQL?)
Requirement: give me all properties of a CustomerMaster for all CustomerMasters where exists at least one PortalCustomerDetailViewModel where
customerMaster.CustomerCode == portalCustomerDetailViewModel.NewNLKNo
|| customerMaster.OldAcNo == portalCustomerDetailViewModel.OldNLKNo
You can't use a normal Join, because a Join works with an AND, you want to work with OR
What you could do, is Select all CustomerMasters where there is any PortalCustomerDetailViewModel that fulfills the provided OR:
I only transfer those properties of list.PortalCustomerDetailViewModel to the database that I need to use in the OR expression:
var checkProperties = list.PortalCustomerDetailViewModel
.Select(portalCustomerDetail => new
{
NewNlkNo = portalCustomerDetail.NewNlkNo,
OldNLKNo = portalCustomerDetail.OldNLKNo,
});
var result = dbContext.CustomerMasters.Where(customerMaster =>
checkProperties.Where(checkProperty =>
customerMaster.CustomerCode == checkProperty.NewNLKNo
|| customerMaster.OldAcNo == checkProperty.OldNLKNo)).Any()))
.Select(customerMaster => new CustomerInfoViewModel
{
Id = customerMaster.Id,
Name = customerMaster.Name,
...
});
In words: from each portalCustomerDetail in list.PortalCustomerDetailViewModel, extract the properties NewNKLNo and OldNLKNo.
Then from the table of CustomerMasters, keep only those customerMasters that have at least one portalCustomerDetail with the properties as described in the OR statement.
From every remaining CustomerMasters, create one new CustomerInfoViewModel containing properties ...
select cm.* from Customer cm
inner join #temp tmp
on cm.CustomerCode = tmp.NewNLKNo or cm.OldAcNo = tmp.OldNLKNo
You don't have to use the join syntax. Adding the predicates in a where clause could get the same result. Try to use the following code:
await (from cm in Context.CustomerMaster
from li in list.PortalCustomerDetailViewModel
where cm.CustomerCode == li.NewNLKNo || cm.OldAcNo = li.OldNLKNo
select new CustomerInfoViewModel
{
CustomerId = cm.Id,
CustomerCode = cm.CustomerCode,
CustomerFullName = cm.CustomerFullName,
OldCustomerCode = cm.OldCustomerCode,
IsCorporateCustomer = cm.IsCorporateCustomer
}).ToListAsync();
var result=_db.Customer
.groupjoin(_db.#temp ,jc=>jc.CustomerCode,c=> c.NewNLKNo,(jc,c)=>{jc,c=c.firstordefault()})
.groupjoin(_db.#temp ,jc2=>jc2.OldAcNo,c2=> c2.OldNLKNo,(jc2,c2)=>{jc2,c2=c2.firstordefault()})
.select(x=> new{
//as you want
}).distinct().tolist();
I have the following criteria and detachedCriteria.
var criteria = Session.CreateCriteria<ItemAnalysis>("ia");
criteria.CreateAlias("ia.ItemInstance", "ii");
criteria.CreateAlias("ii.ScoreAdministration", "sa");
criteria.Add(Restrictions.Eq("ii.ItemId", itemId));
var status = DetachedCriteria.For<ItemAnalysis>("ia_")
.CreateAlias("ia_.ItemInstance", "ii_")
.CreateAlias("ii_.ScoreAdministration", "sa_")
.Add(Restrictions.Eq("ii_.ItemId", itemId))
.SetProjection(
Projections.SqlProjection
(
"ia_.CTTItemStatId, RANK() OVER(Partition BY
sa_.ExamSeriesCode ORDER BY ia_.StatDate DESC) AS RowNm",
new string[] { "CTTItemStatId", "RowNm" },
new IType[] { NHibernate.NHibernateUtil.Int32,
NHibernate.NHibernateUtil.Int32 }
)
);
I need a way to get a projection or second subquery from the detached query that has just that property and adds a restriction of RowNm=1. I looked at DetachedCriteria.CreateCriteria but that requires an Association Path. I haven't found any similar examples. I did try
// what parameters should I be using here??
var subQuery = status.CreateCriteria(?, ?) // expects an association path and an alias
.Add(Restrictions.Eq("RowNm", 1))
.SetProjection(
Projections.Property("CTTItemStatId")
);
criteria = criteria.Add(Subqueries.PropertyEq("CTTItemStatId", subQuery));
Im working in a backend API using Java and MySql, and I'm trying to use #SqlResultSetMapping in JPA 2.1 for mapping a ONE-TO-MANY native query result into a POJO class, this is the native query:
#NamedNativeQuery(name = "User.getAll”, query = "SELECT DISTINCT t1.ID, t1.RELIGION_ID t1.gender,t1.NAME,t1.CITY_ID , t2.question_id, t2.answer_id FROM user_table t1 inner join user_answer_table t2 on t1.ID = t2.User_ID“,resultSetMapping="userMapping")
And, here is my result SQL mapping:
#SqlResultSetMapping(
name = "userMapping",
classes = {
#ConstructorResult(
targetClass = MiniUser.class,
columns = {
#ColumnResult(name = "id"),
#ColumnResult(name = "religion_id"),
#ColumnResult(name = "gender"),
#ColumnResult(name = "answers"),
#ColumnResult(name = "name"),
#ColumnResult(name = "city_id")
}
),
#ConstructorResult(
targetClass = MiniUserAnswer.class,
columns = {
#ColumnResult(name = "question_id"),
#ColumnResult(name = "answer_id")
}
)
})
And, here is the implementation of the POJO classes: (I just removed the constructor and the getters/setter)
MiniUser class
public class MiniUser {
String id;
String religionId;
Gender gender;
List<MiniUserAnswer> answers;
String name;
String city_id;
}
and the MiniUserAnswer class
public class MiniUserAnswer {
String questionId;
String answerId;
}
My goal is to execute this Query and return a list of MiniUser, and in each MiniUser: a list of his “answers", which is a list of MiniUserAnswer.
after running this code, I got this error:
The column result [answers] was not found in the results of the query.
I know why, it's because there is no “answers" field in the query select statement.
So, how can I accomplish something like this, considering the performance? This answers list may reach 100.
I really appreciate your help, Thanks in advance!
The query "SELECT DISTINCT t1.ID, t1.RELIGION_ID t1.gender, t1.NAME, t1.CITY_ID, t2.question_id, t2.answer_id" does not return a parameter called answers.
To obtain the result you are looking for I would use:
Option 1 (Criteria Builder)
CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery<UserTableEntity> cq = cb.createQuery(UserTableEntity.class);
Root<UserTableEntity> rootUserTable = cq.from(UserTableEntity.class);
Join<UserTableEntity,UserAnswerTableEntity> joinAnswerTable = rootUserTable.join(rootUserTable_.id) // if the relationship is defined as lazy, use "fetch" instead of "join"
//cq.where() NO WHERE CLAUSE
cq.select(rootUserTable)
entityManager.createQuery(cq).getResultList();
Option 2 (Named query, not native)
#NamedQuery(name = "User.getAll”, query = "SELECT t1 FROM UserTableEntityt1 join fetch t1.answers)
Option 3 (Entity subgraph, new in JPA 2.1)
In User Entity class:
#NamedEntityGraphs({
#NamedEntityGraph(name = "graph.User.Answers", attributeNodes = #NamedAttributeNode("answers"))
})
In DAO set hints in the entity manager:
EntityGraph graph = this.em.getEntityGraph("graph.User.Answers");
Map hints = new HashMap();
hints.put("javax.persistence.fetchgraph", graph);
I'm stumped trying to convert the following sql to linq:
SELECT t.* FROM(SELECT mwfieldid,MAX([TimeStamp]) AS MaxValue, BatchDocumentID
FROM mw_BatchField
GROUP BY mwfieldid,BatchDocumentID) x
JOIN mw_BatchField t ON x.mwfieldid = t.mwfieldid
AND x.MaxValue = t.TimeStamp
and x.BatchDocumentID = t.BatchDocumentID
So far I had to convert it to a stored proc to get it to work. I'd rather know how to write this correctly in linq. I tried using a sql to linq converter (http://www.sqltolinq.com/) which produced this code that had errors in it: (Are these converters any good? It didn't seem to produce anything useful with a few tries.)
From x In (
(From mw_BatchFields In db.mw_BatchFields
Group mw_BatchFields By
mw_BatchFields.MWFieldID,
mw_BatchFields.BatchDocumentID
Into g = Group
Select
MWFieldID,
MaxValue = CType(g.Max(Function(p) p.TimeStamp),DateTime?),
BatchDocumentID)
)
Join t In db.mw_BatchFields
On New With { .MWFieldID = CInt(x.MWFieldID), .MaxValue = CDate(x.MaxValue), .BatchDocumentID = CInt(x.BatchDocumentID) }
Equals New With { .MWFieldID = t.MWFieldID, .MaxValue = t.TimeStamp, .BatchDocumentID = t.BatchDocumentID }
Select
BatchFieldID = t.BatchFieldID,
BatchDocumentID = t.BatchDocumentID,
MWFieldID = t.MWFieldID,
TimeStamp = t.TimeStamp,
value = t.value,
DictionaryValue = t.DictionaryValue,
AutoFilled = t.AutoFilled,
employeeID = t.employeeID
Seems like a lot of code for such a simple query, and it doesn't compile.
So for every combination of mwfieldid and BatchDocumentID you want all columns of the row with the highest TimeStamp? This is something which is much easier to express in LINQ than SQL so I'm not surprised that an automated converter is making a meal of it.
You should be able to do:
Mw_BatchFields.GroupBy(x => new { x.Mwfieldid, x.BatchDocumentId })
.SelectMany(x => x.Where(y => y.TimeStamp == x.Max(z => z.TimeStamp)))
This (like your SQL) will return multiple rows per grouping key if there is more than one row in the group that shares the same maximum TimeStamp. If you only want row per key, you could use:
Mw_BatchFields.GroupBy(x => new { x.Mwfieldid, x.BatchDocumentId })
.Select(x => x.OrderByDescending(y => y.TimeStamp).First())
Edit:
Sorry, just twigged that you're working in VB, not C#, so not quite what you were looking for, but if you can live with the lambda syntax style, I think the above can be translated as:
Mw_BatchFields.GroupBy(Function(x) New With {x.Mwfieldid, x.BatchDocumentId}).Select(Function(x) x.OrderByDescending(Function(y) y.TimeStamp).First())
and:
Mw_BatchFields.GroupBy(Function(x) New With {x.Mwfieldid, x.BatchDocumentId}).SelectMany(Function(x) x.Where(Function(y) y.TimeStamp = x.Max(Function(z) z.TimeStamp)))
My LINQ query contains the following Group By statement:
Group p By Key = New With { _
.Latitude = p.Address.GeoLocations.FirstOrDefault(Function(g) New String() {"ADDRESS", "POINT"}.Contains(g.Granularity)).Latitude, _
.Longitude = p.Address.GeoLocations.FirstOrDefault(Function(g) New String() {"ADDRESS", "POINT"}.Contains(g.Granularity)).Longitude}
The query works, but here is the SQL that the clause above produces
SELECT [t6].[Latitude]
FROM (
SELECT TOP (1) [t5].[Latitude]
FROM [dbo].[GeoLocations] AS [t5]
WHERE ([t5].[Granularity] IN (#p0, #p1)) AND ([t5].[AddressId] = [t2].[Addr_AddressId])
) AS [t6]
) AS [value], (
SELECT [t8].[Longitude]
FROM (
SELECT TOP (1) [t7].[Longitude]
FROM [dbo].[GeoLocations] AS [t7]
WHERE ([t7].[Granularity] IN (#p2, #p3)) AND ([t7].[AddressId] = [t2].[Addr_AddressId])
) AS [t8]
) AS [value2]
I am not a SQL expert, but it looks to me that this is rather suboptimal translation. This should really be one query that selects Latitide and Longitude from the first record. Perhaps SQL Server Optimizer will take care of this. But is there a way to nudge Linq to generate a leaner SQL statement to begin with?
I tried the following, too..
Group p By Key = p.Address.GeoLocations.Where(Function(g) New String() {"ADDRESS", "POINT"}.Contains(g.Granularity)). _
Select(Function(g) New With {.Latitude = g.Latitude, .Longitude = g.Longitude}).FirstOrDefault
but this produced an error: "A group by expression can only contain non-constant scalars that are comparable by the server."
Sorry to reply in c#...
Here's what you have, translated to c#:
List<string> params = new List<string>()
{ "Address", "Point" };
from p in people
group p by new {
Latitude = p.Address.GeoLocations
.FirstOrDefault(g => params.Contains(g.Granularity)).Latitude,
Longitude = p.Address.GeoLocations
.FirstOrDefault(g => params.Contains(g.Granularity)).Longitude
};
Here's a rewrite, using the let keyword.
from p in people
let loc = p.Address.GeoLocations
.FirstOrDefault(g => params.Contains(g.Granularity))
group p by new
{
Latitude = loc.Latitude,
Longitude = loc.Longitude
};