I am wondering can I do a where clause that takes in a collection?
List<string> myStrings = new List<strings> {"1", "2"};
session.Query<Table>().Where(x => x.Id == myStrings).ToList();
I basically want to get all rows from my db table that match everything in that query.
session.Query<Table>().Where(x => x.Id == myStrings[0]).ToList();
session.Query<Table>().Where(x => x.Id == myStrings[1]).ToList();
session.Query<Table>().Where(x => x.Id == myStrings[N]).ToList();
So thats what I would have to do right now. I would probably through that in a for loop but that is alot of queryies and I rather just do one query.
Or do I have to use the nhibernate create query syntax
var query = "Select * From Where In (:Id)";
session.CreateQuery(query)SetParameter("Id",myStrings) // not sure if I have to something like .ExecuteUpdate(); but just for select instead
session.Query<Table>().Where(x => myStrings.Contains(s => x.Id));
session.Query<Table>().Where(x => myString.All(s => x.Id == s));
you should use Any or All extension method on your collection
Related
Finally tracked down my error which is a result of the query. I have an nhibernate query using a Restrictions.In. Problem is once query executes if no results returned query throws error immediately. Is there another restriction that I can use. I know if I was writing a linq query I could use the .Any to return bool value and go from there is there something similar I can do in this instance?
carMake is passed in
myQuery.JoinQueryOver(x => x.Car)
.Where(Restrictions.In("VIN",
Trades.Where(x => x.Car.Make.ToLower() == carMake.ToLower())
.Select(x => x.Car.PrimaryVIN)
.ToList()));
Assuming that Trades is a list of objects you can use .WhereRestrictionOn() instead. Try this (I split the code for better readability):
var vinsWithCarMake = Trades
.Where(x => x.Car.Make.ToLower() == carMake.ToLower())
.Select(x => x.Car.PrimaryVIN)
.ToList<string>();
var carAlias = null;
var result = myQuery.JoinAlias(x => x.Car, () => carAlias)
.WhereRestrictionOn(() => carAlias.VIN).IsInG<string>(vinsWithCarMake)
.List();
I have a problem with translating this SQL into QueryOver notation. Can you help me?
SELECT * FROM Alerts a
WHERE a.CreatedOn = (
SELECT MAX(b.CreatedOn) FROM Alerts b WHERE b.UserFk=a.UserFk);
I try to select last alert for every user. I use CreatedOn and cannot use Id.
I have so far:
session.QueryOver(() => alertAlias)
.SelectList(list => list
.Select(() => alertAlias.User.Id)
.SelectSubQuery(
QueryOver.Of<Alerts>()
.Where(x => x.User.Id == alertAlias.User.Id)
.OrderBy(x => x.CreatedOn).Desc
.Select(x => x.CreatedOn)
.Take(1)));
I know it adds user's last alert date to every user's alert row. But I want to have only last alerts.
Your attempt is using subquery inside of a SELECT statement. But we need to move it into WHERE. This should be the way:
// this is a subquery (SELECT ....
var subquery = QueryOver.Of<Alerts>()
.Where(x => x.User.Id == alertAlias.User.Id)
.OrderBy(x => x.CreatedOn).Desc
.Select(x => x.CreatedOn)
.Take(1)));
// main Query could now have or do not have that subquery selected
var query = session.QueryOver(() => alertAlias)
.SelectList(list => list
.Select(() => alertAlias.User.Id)
// could be there
.SelectSubQuery(subquery)
)
// but mostly here we do use WHERE clause
.WithSubquery
.WhereProperty(() => alertAlias.CreatedOn)
.Eq(subquery)
;
// such a query could be returned as a list of arrays
var results = query.List<object[]>();
We can also use some Result Transformer, but this is another story...
I have some QueryOver with several joins and the result I get is OK in terms of the returned objects. This is the code>
var l = session.QueryOver<Discount>(() => discount)
.JoinQueryOver<ConPrdGrp>(r => r.ConPrdGrps)
.JoinQueryOver<PrdGroupTree>(k => k.PrdGroupTree)
.JoinQueryOver<Product>(g => g.Products)
.Where(p => p.ProductID == Product.ProductID)
.And(() => discount.FomDato <= DateTime.Now && discount.TomDato >= DateTime.Now).List();
But if I look at the SQL statement, I can see that the generated query selects ALL columns from all joined tables although the result only returns a list of Discount objects. I can get some properties of Discount using projections and the query will be much smaller. But how I can instruct NHibernate to get just columns from the Discount table and not from all joined tables?
As far as I know there is NOT a simple way like: .Select(Projections.Properties<Discount>()). Check this a bit outdated question (NHIbernate: Shortcut for projecting all properties?)
What you can do is explicitly name the columns you would like to see:
... // the QueryOver you have
.SelectList (l => l
.Select(() => discount.ID).WithAlias(() => discount.ID)
.Select(() => discount.Code).WithAlias(() => discount.Code)
...
)
.TransformUsing(Transformers.AliasToBean<Discount>())
...
The second approach could be to create the Subquery, and then just QueryOver<Discount>() 16.8. Subqueries
QueryOver<Discount> subQuery =
QueryOver.Of<Discount>(() => innerDiscount)
.JoinQueryOver<ConPrdGrp>(r => r.ConPrdGrps)
.JoinQueryOver<PrdGroupTree>(k => k.PrdGroupTree)
.JoinQueryOver<Product>(g => g.Products)
.Where(p => p.ProductID == Product.ProductID)
.And(() => innerDiscount.FomDato <= DateTime.Now
&& innerDiscount.TomDato >= DateTime.Now).List()
.Select( Projections.Property(() => innerDiscount.ID))
;
var query = session.QueryOver<Discount>(() => discount)
.Where(Subqueries.PropertyIn("ID", subQuery.DetachedCriteria))
;
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've a little problem: I would insert a condition into my QueryOver that checks also the variable value. Something like this:
var qOver = QueryOver.Of<MyModel>(() => myMod)
.JoinAlias(() => myMod.SubMod, () => subMod, JoinType.LeftOuterJoin)
.Where(Restrictions.Or(
Restrictions.On(() => myMod.ID).IsIn(MyIDList)
, Restrictions.On(MyIDList == null))
In SQL sintax something like
WHERE #Variable = '' OR MyTable.MyField = #Variable
So, if I my variable is filled I'll filter on my field. If my variable is empty (or null) I'll select every record without filter any content.
How can I reach this result using QueryOver and Restrinctions?
Thank you!
If the variable is null or not set, dont add it to your query.
var qOver = QueryOver.Of<MyModel>(() => myMod)
.JoinAlias(() => myMod.SubMod, () => subMod, JoinType.LeftOuterJoin);
if( MyIDList != null )
qOver = qOver.Where(Restrictions.Or(Restrictions.On(() => myMod.ID).IsIn(MyIDList))