When I specify the following formula:
Map(x => x.PendingInviteCount)
.Access
.ReadOnly()
.Formula("(SELECT COUNT(ui.UserInviteId)
FROM [UserInvite] ui JOIN [UserInviteOrganisation] uio
ON ui.UserInviteId = uio.UserInviteId
WHERE uio.OrganisationId = organisationId)");
the sql that is generated looks like this:
SELECT COUNT(ui.UserInviteId)
FROM [UserInvite] ui
JOIN [UserInviteOrganisation] organisati0_.uio on ui.UserInviteId = uio.UserInviteId
WHERE uio.OrganisationId = organisati0_.organisationId
which fails due to uio being prefixed with organisatio0_.
Is it possible to create a formula that contains a JOIN?
You should use the AS keyword for setting the alias of the table. I don't think that NHibernate picks up on it the way it is currently written.
Related
I've been working on improving performance for our .NET core API with EF 5.0.11 by reducing the projection of our queries, but I'm currently stuck with the following scenario:
I improved the projection of the queries like this:
var employeeEmailQuery = context.Employee
.Where(e => e.Active == true)
.Select(e => new EmployeeEmailView
{
Name = e.FullName,
Email = e.Email
});
This reduces the select query to just the two columns I need instead of a SELECT * on 80+ columns in the database.
In my database, I also have columns with translated descriptions. It looks like this:
What I would like to do is select the relevant translated description, based on the current culture, so I added the following code:
var culture = CultureInfo.DefaultThreadCurrentUICulture;
var employeeEmailQuery = context.Employee
.Where(e => e.Active == true)
.Select(e => new EmployeeEmailView
{
Name = e.FullName,
Email = e.Email,
this.SetDescription(e, culture);
});
The SetDescription method checks the culture and picks the correct column to set a Description property in the EmployeeEmailView. However, by adding this code, the query is now once again doing a SELECT *, which I don't want.
Does anybody have an idea on how to dynamically include a select column using EF without rewriting everything into raw SQL?
Thanks in advance.
I think the only way is to use an Interceptor to modify the query, or dynamically generate the EF IQueryable with Expressions.
I'm using Xeditable and RABL in a Rails app.
I have a workorder that belongs to a workgroup.
I want to assign the workorder to an employee in that workgroup.
I'm using this as the source in the Xeditable:
data-source="/employees.json?workgroup=<%= workorder.workgroup.id%>"
And this is the code I'm trying in the employee controller:
def index
#employees = Employee.order(:first_name)
#employees = Employee.joins(:empgroups).where(:workgroup_id => params[:workgroup]) if params[:workgroup].present?
end
This is the SQL that gets generated:
SELECT "employees".* FROM "employees" INNER JOIN "empgroups" ON "empgroups"."employee_id" = "employees"."id" WHERE "employees"."workgroup_id" = 2
The issue is the WHERE should be `WHERE "empgroups"."workgroup_id" = 2
How do I change this line of code?
#employees = Employee.joins(:empgroups).where(:workgroup_id => params[:workgroup]) if params[:workgroup].present?
Thanks for the help!
You can use nested hash syntax:
#employees = Employee.joins(:empgroups).where(
empgroups: { workgroup_id: params[:workgroup] }
) if params[:workgroup].present?
This should work:
Employee.joins(:empgroups).where(:empgroups => {:workgroup_id => params[:workgroup]})
The :workgroup_id is actually an attribute/column on a joined table, and not on the base table that you are querying from, so you need to specify where that column is located during the where clause.
Remember that in a pinch you can also type in SQL for the where clause, but will also have to remember to properly reference the right table.
Employee.joins(:empgroups).where("empgroups.workgroup_id = ?", params[:workgroup])
I am new to entity framework and learning making queries. Can anyone please help me how can I convert the following SQL query to run in entity framework?
select max(isnull(TInvoice.InvoiceNr, 0)) + 1
from TInvoice inner join TOrders
on TInvoice.OrderId = TOrders.OrderId
where TOrders.ClientFirmId = 1
As comments have said, without the data model it is hard to be exact.
Would really need to see how you have defined your relations in your data model.
I guess from first read my first impression is something along the lines of:
int max = context.TInvoice.Where(x => x.TOrders.ClientFirmId == 1).Max(x => x.InvoiceNr);
First off, I'm a Ruby/Rails newbie, so I apologize if this question is basic.
I've got a DB that (among other things) looks like this:
organizations { id, name, current_survey_id }
surveys { id, organization_id }
responses { id, survey_id, question_response_integer }
I'm trying to create a scope method that adds the average of the current survey answers to a passed-in Organization relation. In other words, the scope that's getting passed into the method would generate SQL that looks like more-or-less like this:
select * from organizations
And I'd like the scope, after it gets processed by my lambda, to generate SQL that looks like this:
select o.id, o.name, cs.average_responses
from organizations o join
(select r.id, avg(r.question_response_integer) as average_responses
from responses r
group by r.id) cs on cs.id = o.current_survey_id
The best I've got is something like this:
current_survey_average: lambda do |scope, sort_direction|
average_answers = Responses.
select("survey_id, avg(question_response_integer) as average_responses").
group("survey_id")
scope.joins(average_answers).order("average_responses #{sort_direction}")
end
That's mostly just a stab in the dark - among other things, it doesn't specify how the scope could be expected to join to average_answers - but I haven't been able to find any documentation about how to do that sort of join, and I'm running out of things to try.
Any suggestions?
EDIT: Thanks to Sean Hill for the answer. Just to have it on record, here's the code I ended up going with:
current_survey_average: lambda do |scope, sort_direction|
scope_table = scope.arel.froms.first.name
query = <<-QUERY
inner join (
select r.survey_id, avg(r.question_response_integer) as average_responses
from responses r
group by r.survey_id
) cs
on cs.survey_id = #{scope_table}.current_survey_id
QUERY
scope.
joins(query).
order("cs.average_responses #{sort_direction}")
end
That said, I can see the benefit of putting the averaged_answers scope directly onto the Responses class - so I may end up doing that.
I have not been able to test this, but I think the following would work, either as-is or with a little tweaking.
class Response < ActiveRecord::Base
scope :averaged, -> { select('r.id, avg(r.question_response_integer) as average_responses').group('r.id') }
scope :current_survey_average, ->(incoming_scope, sort_direction) do
scope_table = incoming_scope.arel.froms.first.name
query = <<-QUERY
INNER JOIN ( #{Arel.sql(averaged.to_sql)} ) cs
ON cs.id = #{scope_table}.current_survey_id
QUERY
incoming_scope.joins(query).order("average_responses #{sort_direction}")
end
end
So what I've done here is that I have split out the inner query into another scope called averaged. Since you do not know which table the incoming scope in current_survey_average is coming from, I got the scope table name via scope.arel.froms.first.name. Then I created a query string that uses the averaged scope and joined it using the scope_table variable. The rest is pretty self-explanatory.
If you do know that the incoming scope will always be from the organizations table, then you don't need the extra scope_table variable. You can just hardcode it into the join query string.
I would make one suggestion. If you do not have control over sort_direction, then I would not directly input that into the order string.
I have this SQL expression:
SELECT Musclegroups.Name, COUNT(DISTINCT Workouts.WorkoutID) AS Expr1
FROM Workouts INNER JOIN
Series ON Workouts.WorkoutID = Series.WorkoutID INNER JOIN
Exercises ON Series.ExerciseID = Exercises.ExerciseID INNER JOIN
Musclegroups ON Musclegroups.MusclegroupID = Exercises.MusclegroupID
GROUP BY Musclegroups.Name
Since Im working on a project which uses EF in a WCF Ria LinqToEntitiesDomainService, I have to query this with LINQ (If this isn't a must then pls inform me).
I made this expression:
var WorkoutCountPerMusclegroup = (from s in ObjectContext.Series1
join w in ObjectContext.Workouts on s.WorkoutID equals w.WorkoutID
where w.UserID.Equals(userid) && w.Type.Equals("WeightLifting")
group s by s.Exercise.Musclegroup into g
select new StringKeyIntValuePair
{
TestID = g.Select(n => n.Exercise.MusclegroupID).FirstOrDefault(),
Key = g.Select(n => n.Exercise.Musclegroup.Name).FirstOrDefault(),
Value = g.Select(n => n.WorkoutID).Distinct().Count()
});
The StringKeyIntValuePair is just a custom Entity type I made so I can send down the info to the Silverlight client. Also this is why I need to set an "TestID" for it, as it is an entity and it needs one.
And the problem is, that this linq query produces this horrible SQL statement:
http://pastebay.com/144532
I suppose there is a better way to query this information, a better linq expression maybe. Or is it possible to just query with plain SQL somehow?
EDIT:
I realized that the TestID is unnecessary because the other property named "Key" (the one on which Im grouping) becomes the key of the group, so it will be a key also. And after this, my query looks like this:
var WorkoutCountPerMusclegroup = (from s in ObjectContext.Series1
join w in ObjectContext.Workouts on s.WorkoutID equals w.WorkoutID
where w.UserID.Equals(userid) && w.Type.Equals("WeightLifting")
group w.WorkoutID by s.Exercise.Musclegroup.Name into g
select new StringKeyIntValuePair
{
Key = g.Key,
Value = g.Select(n => n).Distinct().Count()
});
This produces the following SQL: http://pastebay.com/144545
This seems far better then the previous sql statement of the half-baked linq query.
But is this good enough? Or this is the boundary of LinqToEntities capabilities, and if I want even more clear sql, I should make another DomainService which operates with LinqToSQL or something else?
Or the best way would be using a stored procedure, that returns Rowsets? If so, is there a best practice to do this asynchronously, like a simple WCF Ria DomainService query?
I would like to know best practices as well.
Compiling of lambda expression linq can take a lot of time (3–30s), especially using group by and then FirstOrDefault (for left inner joins meaning only taking values from the first row in the group).
The generated sql excecution might not be that bad but the compilation using DbContext which cannot be precompiled with .NET 4.0.
As an example 1 something like:
var q = from a in DbContext.A
join b ... into bb from b in bb.DefaultIfEmtpy()
group new { a, b } by new { ... } into g
select new
{
g.Key.Name1
g.Sum(p => p.b.Salary)
g.FirstOrDefault().b.SomeDate
};
Each FirstOrDefault we added in one case caused +2s compile time which added up 3 times = 6s only to compile not load data (which takes less than 500ms). This basically destroys your application's usability. The user will be waiting many times for no reason.
The only way we found so far to speed up the compilation is to mix lambda expression with object expression (might not be the correct notation).
Example 2: refactoring of previous example 1.
var q = (from a in DbContext.A
join b ... into bb from b in bb.DefaultIfEmtpy()
select new { a, b })
.GroupBy(p => new { ... })
.Select(g => new
{
g.Key.Name1
g.Sum(p => p.b.Salary)
g.FirstOrDefault().b.SomeDate
});
The above example did compile a lot faster than example 1 in our case but still not fast enough so the only solution for us in response-critical areas is to revert to native SQL (to Entities) or using views or stored procedures (in our case Oracle PL/SQL).
Once we have time we are going to test if precompilation works in .NET 4.5 and/or .NET 5.0 for DbContext.
Hope this helps and we can get other solutions.