Given the following information, how can I combine these 2 linq queries into 1. Having a bit of trouble with the join statement.
'projectDetails' is just a list of ProjectDetails
ProjectDetails (1 to many) PCardAuthorizations
ProjectDetails (1 to many) ExpenditureDetails
Notice I am grouping by the same information and selecting the same type of information
var pCardAccount = from c in PCardAuthorizations
where projectDetails.Contains(c.ProjectDetail)
&& c.RequestStatusId == 2
group c by new { c.ProjectDetail, c.ProgramFund } into g
select new { Key = g.Key, Sum = g.Sum(x => x.Amount) };
var expenditures = from d in ExpenditureDetails
where projectDetails.Contains(d.ProjectDetails)
&& d.Expenditures.ExpenditureTypeEnum == 0
group d by new { d.ProjectDetails, d.ProgramFunds } into g
select new {
Key = g.Key,
Sum = g.Sum(y => y.ExpenditureAmounts.FirstOrDefault(a => a.IsCurrent && !a.RequiresAudit).CommittedMonthlyRecords.ProjectedEac)
};
I don't think Mike's suggestion will work here. These two queries are sufficiently different that combining them into one query will just make it more difficult to read.
The objects have different types.
The where clauses are different.
The group by clause is different:
new { c.ProjectDetail, c.ProgramFund }
new { c.ProjectDetails, c.ProgramFunds }
The select clauses are different.
In fact there isn't really anything that is the same. I'd recommend leaving it as it is.
You could always just concat them together before evaluating them.
pCardAccount.Concat(expenditures).ToArray()
should generate a single sql statement with a union. As to whether there is any benefit to this in your situation, I don't know. There's also a chance that linq-to-sql won't be able to generate the SQL for the concat and will throw an exception whenever you use it. I'm not sure what causes it, but I've seen it a few times when I was playing around in a similar situation.
Edit: I just noticed that your keys are different in each of the queries. I'm not sure if this is a typo or not, but if it isn't, you won't be able to concat them due to the different types and it wouldn't make any sense to anyway
Related
I am trying to compare two tables (i.e values, count, etc..) in linq to sql but I am not getting the way to achieve it. I tried the following,
Table1.Any(i => i.itemNo == Table2.itemNo)
It gives error. Could you please help me?
Thanks in Advance.
how about
var isDifferent =
Table1.Zip(Table2, (j, k) => j.itemNo == k.itemMo).Any(m => !m);
EDIT
if Linq-To-Sql does not support Zip.
var one = Table1.ToList();
var two = Table2.ToList();
var isDifferent =
one.Zip(two, (j, k) => j.itemNo == k.itemMo).Any(m => !m);
if the tables are vary large this could cause performance problems. In that case you will need a much more sophisticated solution, if so, please ask.
EDIT2
If the tables are very large you don't want to get all the data from the server and hold it memory. Additionaly, Linq and SQL server do not garauntee the order of the rows unless you specify an order in the query. This becomes espcially relavent for large result sets returned by a multi processor server where the effects of parallelism are likely to come into play.
I suggest that Linq-to-Sql doesen't really cater well for your scenario so you will have to help it out using ExecuteQuery somthing like this.
string zipQuery =
#"SELECT TOP 1
1
FROM
[Table1] [one]
WHERE
NOT EXISTS (
SELECT * FROM [Table2] [two] WHERE [two].[itemNo] = [one].[itemNo]
)
UNION ALL
SELECT
1
FROM
[Table2] [two]
WHERE
NOT EXISTS (
SELECT * FROM [Table1] [one] WHERE [one].[itemNo] = [two].[itemNo]
)
UNION ALL
SELECT 0";
var isDifferent = context.ExecuteQuery<int>(zipQuery).Single() == 1;
This will do the select on the server without returning lots of data to the client but, I think you will agree is much more complicated.
EDIT3
Okay, the zip approach should be fine for 1000 rows. I've read your comment and I suggest changing the code accordingly.
var one = Table1.ToList();
var two = Table2.ToList();
var isDifferent =
one.Count != two.Count ||
one.Zip(two, (o, t) => o.itemNo == k.itemNo).Any(m => !m);
You should probably consider putting an order by on the list retrievers, like this.
var one = Table1.OrderBy(o => o.itemNo).ToList();
Strictly, the results of a Linq-to-Sql come back in any order unless an order is specified.
So I have a list(table) of about 100k items and I want to retrieve all values that match a given list.
I have something like this.
the Table Sections key is NOT a primary key, so I'm expecting each value in listOfKeys to return a few rows.
List<int> listOfKeys = new List<int>(){1,3,44};
var allSections = Sections.Where(s => listOfKeys.Contains(s.id));
I don't know if it makes a difference but generally listOfKeys will only have between 1 to 3 items.
I'm using the Entity Framework.
So my question is, is this the best / fastest way to include a list in a linq expression?
I'm assuming that it isn't better to use another .NETICollection data object. Should I be using a Union or something?
Thanks
Suppose the listOfKeys will contain only small about of items and it's local list (not from database), like <50, then it's OK. The query generated will be basically WHERE id in (...) or WHERE id = ... OR id = ... ... and that's OK for database engine to handle it.
A Join would probably be more efficient:
var allSections =
from s in Sections
join k in listOfKeys on s.id equals k
select s;
Or, if you prefer the extension method syntax:
var allSections = Sections.Join(listOfKeys, s => s.id, k => k, (s, k) => s);
Can anybody tell me how I would get the records in the first statement that are not in the second statement (see below)?
from or in TblOrganisations
where or.OrgType == 2
select or.PkOrgID
Second query:
from o in TblOrganisations
join m in LuMetricSites
on o.PkOrgID equals m.FkSiteID
orderby m.SiteOrder
select o.PkOrgID
If you only need the IDs then Except should do the trick:
var inFirstButNotInSecond = first.Except(second);
Note that Except treats the two sequences as sets. This means that any duplicate elements in first won't be included in the results. I suspect that this won't be a problem since the name PkOrgID suggests a unique ID of some kind.
(See the documentation for Enumerable.Except and Queryable.Except for more info.)
Do you need the whole records, or just the IDs? The IDs are easy...
var ids = firstQuery.Except(secondQuery);
EDIT: Okay, if you can't do that, you'll need something like:
var secondQuery = ...; // As you've already got it
var query = from or in TblOrganisations
where or.OrgType == 2
where !secondQuery.Contains(or.PkOrgID)
select ...;
Check the SQL it produces, but I think it should do the right thing. Note that there's no point in performing any ordering in the second query - or even the join against TblOrganisations. In other words, you could use:
var query = from or in TblOrganisations
where or.OrgType == 2
where !LuMetricSites.Select(m => m.FkSiteID).Contains(or.PkOrgID)
select ...;
Use Except:
var filtered = first.Except(second);
I'm trying to merge these two object but not totally sure how.. Can you help me merge these two result objects?
//
// Create Linq Query for all segments in "CognosSecurity"
//
var userListAuthoritative = (from c in ctx.CognosSecurities
where (c.SecurityType == 1 || c.SecurityType == 2)
select new {c.SecurityType, c.LoginName , c.SecurityName}).Distinct();
//
// Create Linq Query for all segments in "CognosSecurity"
//
var userListAuthoritative3 = (from c in ctx.CognosSecurities
where c.SecurityType == 3 || c.SecurityType == 0
select new {c.SecurityType , c.LoginName }).Distinct();
I think I see where to go with this... but to answer the question the types of the objects are int, string, string for SecurityType, LoginName , and SecurityName respectively
If you're wondering why I have them broken like this is because I want to ignore one column when doing a distinct. Here are the SQL queries that I'm converting to SQL.
select distinct SecurityType, LoginName, 'Segment'+'-'+SecurityName
FROM [NFPDW].[dbo].[CognosSecurity]
where SecurityType =1
select distinct SecurityType, LoginName, 'Business Line'+'-'+SecurityName
FROM [NFPDW].[dbo].[CognosSecurity]
where SecurityType =2
select distinct SecurityType, LoginName, SecurityName
FROM [NFPDW].[dbo].[CognosSecurity]
where SecurityType in (1,2)
You can't join these because the types are different (first has 3 properties in the resulting type, second has two).
If you can tolerate putting a null value in for the 3rd result of the second query this will help. I would then suggest you just do a userListAuthoritative.concat(userListAuthoritative3 ) BUT I think this will not work as the anonymous types generated by the linq will not be of the same class, even tho the structure is the same. To solve that you can either define a CustomType to encapsulate the tuple and do select new CustomType{ ... } in both queries or postprocess the results using select() in a similar fashion.
Acutally the latter select() approach will also allow you to solve the parameter count mismatch by implementing the select with a null in the post-process to CustomType.
EDIT: According to the comment below once the structures are the same the anonymous types will be the same.
I assume that you want to keep the results distinct:
var merged = userListAuthoritative.Concat(userListAuthoritative3).Distinct();
And, as Mike Q pointed out, you need to make sure that your types match, either by giving the anonymous types the same signature, or by creating your own POCO class specifically for this purpose.
Edit
If I understand your edit, you want your Distinct to ignore the SecurityName column. Is that correct?
var userListAuthoritative = from c in ctx.CognosSecurities
where new[]{0,1,2,3}.Contains(c.SecurityType)
group new {c.SecurityType, c.LoginName, c.SecurityName}
by new {c.SecurityType, c.LoginName}
select g.FirstOrDefault();
I'm not exactly sure what you mean by merge, since you're returning different (anonymous) types from each one. Is there a reason the following doesn't work for you?
var userListAuthoritative = (from c in ctx.CognosSecurities
where (c.SecurityType == 1 || c.SecurityType == 2 || c.SecurityType == 3 || c.SecurityType == 0)
select new {c.SecurityType, c.LoginName , c.SecurityName}).Distinct();
Edit: This assumed they were of the same type -- but they're not.
userListAuthoritative.Concat(userListAuthoritative3);
Try below code, you might need to implement IEqualityComparer<T> in your ctx type.
var merged = userListAuthoritative.Union(userListAuthoritative3);
I'm trying to get Entity Framework to select an object and filter its collection at the same time. I have a JobSeries object which has a collection of jobs, what I need to do is select a jobseries by ID and filter all the jobs by SendDate but I can't believe how difficult this simple query is!
This is the basic query which works:
var q = from c in KnowledgeStoreEntities.JobSeries
.Include("Jobs.Company")
.Include("Jobs.Status")
.Include("Category")
.Include("Category1")
where c.Id == jobSeriesId
select c;
Any help would be appreciated, I've been trying to find something in google and what I want to do is here:http://blogs.msdn.com/bethmassi/archive/2009/07/16/filtering-entity-framework-collections-in-master-detail-forms.aspx
It's in VB.NET though and I couldn't convert it to C#.
EDIT: I've tried this now and it doesn't work!:
var q = from c in KnowledgeStoreEntities.JobSeries
.Include("Jobs")
.Include("Jobs.Company")
.Include("Jobs.Status")
.Include("Category")
.Include("Category1")
where (c.Id == jobSeriesId & c.Jobs.Any(J => J.ArtworkId == "13"))
select c;
Thanks
Dan
Include can introduce performance problems. Lazy loading is guaranteed to introduce performance problems. Projection is cheap and easy:
var q = from c in KnowledgeStoreEntities.JobSeries
where c.Id == jobSeriesId
select new
{
SeriesName = c.Name,
Jobs = from j in c.Jobs
where j.SendDate == sendDate
select new
{
Name = j.Name
}
CategoryName = c.Category.Name
};
Obviously, I'm guessing at the names. But note:
Filtering works.
SQL is much simpler.
No untyped strings anywhere.
You always get the data you need, without having to specify it in two places (Include and elsewhere).
No bandwith penalties for retrieving columns you don't need.
Free performance boost in EF 4.
The key is to think in LINQ, rather than in SQL or in materializing entire entities for no good reason as you would with older ORMs.
I've long given up on .Include() and implemented Lazy loading for Entity Framework