C# - Converting A T-sql Query To Linq To Sql With Coalesce And Multiple Join?
Jan 9, 2011
We have two related tables (inventory, inventoryLocalization) and a t-sql query works on them as follows..
select inv.[code],
coalesce(inL.name, inL2.name) as [name],
coalesce(inL.description, inL2.description) as [description]
from dbo.[inventory] inv
left join dbo.[inventoryLocalization] inL on inv.code = inL.code and inL.language = 'de'
left join dbo.[inventoryLocalization] inL2 on inv.code = inL2.code and inL2.language = 'en'
where inv.[code] like '15.' + '%'
order by inv.[code];
to performance improvement, we will try to use these tables from cache not from RDBMS directly.
for an asp.net 4.0 project, by c#. We've took both tables to chache with a DataSet and we can reach both of them through that DataSet.
DataSet ds = UtilityCache.getCachedDataSet();
"ds.Tables[0]" is inventory Table and "ds.Tables[1]" is inventoryLocalization Table
But how can we convert above T-Sql syntax to linq2Sql. is it possible to use coalesce for select statement and to join on two tables with multiple conditions ?
public ActionResult Index() { MembershipUser currentUser = Membership.GetUser(); Guid UserId = (Guid)currentUser.ProviderUserKey; using (var db = new MatchGamingEntities()) { var MyAccount = from m in db.Accounts..........
I want to be able to do a join query between my two tables Accounts and BankTransactions. This is a one to many relationship, there can be multiple BankTransactions per Account. I want to query this and display the account information including all the bank statements that are associated with it. I did a join in order to get it, but I am having trouble handling the model. I keep getting this error:
LINQ to Entities does not recognize the method 'System.Collections.Generic.List1[MatchGaming.Models.BankTransaction] ToList[BankTransaction](System.Collections.Generic.IEnumerable1[MatchGaming.Models.BankTransaction])' method, and this method cannot be translated into a store expression.
I'm having trouble doing a left outer join with multiple generic lists tables. I've been researching for hours and there isn't a whole lot out there on this subject and VB (at least what I found).
I have the following Linq query:
Dim DataForGridview = (From s In S1 _ Join c In C1 On c.ID Equals s.ID _ Join v In V1 On v.ID Equals s.ID _ Select New With { _ .dataFieldID = s.ID, _ .dataField1 = s.dataField1, _ .dataField2 = c.dataField2, _ .dataField3 = c.dataField3, _ .dataField4 = c.dataField4, _ .dataField5 = v.dataField5 _ }).ToList()
S1 has a count of 30. V1 has a count of 20. C1 has a count of 10. This query joins the three but ends up with a count of only 10 based on the datakey ID and, of course, only shows those 10 in the gridview.
I would like to show all 30 from S1 in the gridview with blank fields wherever V1 and C1 do not have data. From what I've read I need to do a left outer join. However, all examples I've found are with two datasets.
I've tried multiple times expanding on what I've found by changing it to a group join and also adding the .DefaultIfEmpty() property in the query, but nothing is working.
How can I change the above query to a left outer join with these multiple tables?
I'm trying to build a linq2Entity/gridview function for a forum, that draws data from multible tables.The result should be: Get the latest 10 threads that user(xx) has replyed in, that is not disabled or has a subject that is not allowed.Include information on the last post, thread owner user, and last post user, in each thread. ere is my code... is returns the correct threads and some that should not be there.
To write a join query with or condition. It means a query has two inner join, here it is possible to fetch the records, if one inner join is true and other is false. I got a record when only two join conditions are true.
For context: First of all, I am new to LINQ, as I have been using SubSonic for quite some time now.
I have two tables, Users, and Affiliates. They both have a very typical schema. The FK that joins them is the UserId field, which is in the Affiliates table. I want to create a LINQ query that pulls the Username from the Users table using the AffiliateId value. The AffiliateId is a primary key of the Affiliates table.
I have tried to accomplish this using many variations of the following code:
[Code]....
In the above query, I expect to get a single row result set. However, I instead receive the entire table of results.
How can I make this work? I have yet to see an example or article out there to do what I am trying to do.
how can I display a linq query in a gridview that has data from multiple tables AND allow the user to edit some of the fields or delete the data from a single table?
I'd like to do this with either a linqdatasource or a linq query. I'm aware I can set the e.Result to the query on the selecting event. I've also been able to build a custom databound control for displaying the linq relations (parent.child).
However, I'm not sure how I can make this work with delete? I'm thinking I may need to handle the delete event with custom code.
I have a quick Linq to SQL question. I am trying to write a Linq query that has multiple where clauses depening on user input. What I would intuitively code is:
Dim arrTerms As Array = txtUserInput.Text.Split(" ") Dim q = From newsitem In db.MyNewsTable _ Where newsitem.Contains(arrTerms) _ Select newsitem Listview1.DataSource = q Listview1.Databind()
Unfortunately, though, the "Contains" operattor does not accept an arraylist, or array, or anything but String.
I was trying to find out how I can join more than 2 tables using the LINQ-to-SQL syntax. For instance, joining 2 tables in SQL:
SELECT * FROM Table1 AS T1 INNER JOIN Table2 AS T2 ON T1.Key=T2.Column1WHERE T2.Key='17';
can be expressed as:
var Result = from T1 in DbContext.Table1 join T2 in DbContext.Table2 on T1.Key equals T2.ForeignKey where T2.Key=17 select new { T1, T2 };
But how would I join 3 or more tables using LINQ? For example:
SELECT * FROM (Table1 AS T1 INNER JOIN Table2 AS T2 ON T1.Key=T2.Column1) INNER JOIN Table3 AS T3 ON T3.Key=T2.Column2 WHERE T2.Key='37';
I've been searching and experimenting and I cannot seem to find any informraiton on this. One example I found involves putting the result for the frist join into a temp object, and then performing the second join. I'm not sure performance-wise if that's the same as doing a 3-table join directly using a single SQL statement.
User, Details, Optional User has fields: ID, FirstName, LastName Details has fields: ID, MyDetails1, MyDetails2, User_ID Optional has fields: ID, MyOptions1, MyOptions2, User_ID There is a 1 to many relationship with User & Detail (User ID & Detail User_ID) There is a 1 to many relationship with User & Optional (User ID & Optional User_ID)
With that said, one user can have many details and/or many optionals
Now I'm trying to build a linq query that will say:
"where user id = x, select FirstName, LastName, all MyDetails1 from every record where User_ID == x, all MyOptions1 from every record where User_ID == x"
After the merge I should have one string that lists the distict user & all of their many fields:
I am new to LINQ. I have a GridView which I am populating using LINQ. My LINQ statement is taking query string from previous page. The query string is in string format. Here is the code:
The main problem is that I recieve the following message:
"base {System.SystemException} = {"Unable to create a constant value of type 'BokButik1.Models.Book-Author'. Only primitive types ('such as Int32, String, and Guid') are supported in this context."}"
based on this LinQ code:
[Code]....
How shall I solve this problem to get a class instance that contain with property title and Book-AuthorID?I also have tried making some dummy by using "allbooks" relation with Code Samples from the address
http://www.hookedonlinq.com/JoinOperator.ashx. Unfortunately, still same problem.
I also have taken account to Int32 due to entity framework http://msdn.microsoft.com/en-us/library/bb896317.aspx. Unfortunatley, still same problem.
Using database with 3 tables and one of them is a many to many relationship. This database is used in relation with entity framework
I am working on a website similar to nerddinner. Is it possible to perform similar join using Linq to entities what is done with linq to sql in nerddinner.I am posting the codes below.
public IQueryable<Dinner> FindByLocation(float latitude, float longitude) { var dinners = from dinner in FindUpcomingDinners() join i in db.NearestDinners(latitude, longitude)
I have the following LINQ query that does a left join:
var results = from v in ctx.dat_Visitor join sp in ctx.vwSP on v.lu_Mentor.ID equals sp.ID into sp2 select new {
[code]...
My problem is that this LINQ query times out on me. I even upped the default timeout from 15 seconds to 120 seconds and it still times out. dat_Visitor has no more than 10 records in it, but vwSP (which is a view) has somewhere around 100,000 records. I know for sure that the timeout has to do with when I attempt to actually return sp2 in the results. If I change my LINQ query to not return sp2 in the results, then it is quick. Without sp2 the query looks like such:
var results = from v in ctx.dat_Visitor join sp in ctx.vwSP on v.lu_Mentor.ID equals sp.ID into sp2 select new { Visitor = v.Name, Tot = sp2.Count() };
Lastly, I'm using the 3.5 framework, but I am having serious thoughts about upgrading the website to 4.0, since I could then use DefaultIfEmpty().
