Ordering Sub-items Within Ordered Items In A Linq To Entities Query?
Aug 25, 2010
I have a few tables, Listings, ListingImages and a few others related to Listings. ListingImages is related to Listings so that you can have many ListingImages per Listing.
When I query this table I do;
[code].....
Now this is fine. However, I now want to sort the ListingImages independently within each Listing (by an ImageOrder column I have in that table).
How can I do this and pass all my Includes(...). Would it be bad form to sort the ListingImages within the View as this solution seems to work?
the best way to do the following (I'm using a simplified example of my actual problem?Say I have a customer ordered items table with fields: oItemId, OrderId, ProductId, ItemPriceI want to query where OrderId >oMin && OrderId <oMaxand for each value of OrderId I want to find the record with the highest ItemPriceso for a single OrderId the query would be:(from o in context.orderItems where OrderId==x orderby o.ItemPrice select o).first()but OrderId isn't a single value. If I modify the where clause then this query would still produce a single record whereas I want a single record per OrderId.oh and as an additional question: does anyone have a compact test for whether a record exists. I am using the querystring to specify an Id and there are numerous things that I want to protect against. If I do:
var myRecord = from o in context.orders where o.orderId == request.querystring["Order"] select othen this fails if the querystring isn't specified. So first I test that the querystring != nul . Then I need to do:bool recordExists = (myRecord != null)because even if the querystring is specified it may be an invalid orderId and thus the query returns no results. Is there a shorter/simpler way to calculate the result. I have not yet got to grips with lambda expressions and I'm not sure whether there is a better approach with lambda expressions.
var result = from category in myEntities.Categories where category.UserId == userId orderby category.CategoryName select category;
What is the type of "result"? I casted it to an IQueryable variable and it worked except it did not have some of the methods normally available, e.g. Count(). In my program I have to cast it to some explicit types and then use the Count() method.
i have a new question: i read all the tutorials that i found but i cannot understand how to pass a result of a linq to entities result to the view so that i can display the results. My query is actually in the controller function ot the view, i would now loop the results and display them in the page. How?
below is the code I have but I want to change the ddl.Deal(dropdownlist) to cbl.Deal(checkboxlist).. How can I loop throught each items if checked. and if all items are checked. to filter my data and show in gridview..
protected void btn_Click(object sender, EventArgs e) { myAPI.myWeb myAPI = new myAPI.myWeb(); myAPI.SearchParameters sSearchParameters = new myAPI.SearchParameters();
I am using Microsoft Visual Studio 2008 Professional Edition on Windows Vista Home Basic SP2 and when I am editing Visual Basic and want to add an item to the toolbox I click on Choose Items... and from that point I can't find important controls (items) like Windows Media Player or Adobe PDF Viewer. I have tried to reinstall and reset the toolbox and program. I can't find this problem anywhere in the web
I want to delete the items in db using linq to sql below is my code
[Code]....
here i am very much confused about this var delt= from x what is x here? and dc2.emps.deleteonsubmit (here what is emps?)i am getting errors like emp id doesnt exist in the current context.
I have 4 Checkboxlists, if i check 1st item of checkboxlist1 -- > populate items in checkboxlist2 if i check 2nd item in checkboxlist1 -- >populate items in checkboxlist2 with last selection as well as 1st checkboxlist items. So I need to Append items in Checkboxlist with existing items and also with previously selected Checkox. Is it any way except DataTable ?
I'm having trouble writing what should be a simple sub-query using LINQ to Entities. I have two tables: Customers and Orders that have a relation on the CustID field. Not all Customers have a record in the Orders table, while some have mutiple records. In traditional SQL, you could write the query like this: SELECT * FROM Orders where CustID IN (SELECT CustID FROM Customers) I know this could be done as a JOIN in both SQL and L2E, but my actual query is more complex (about 8-9 joins), so I am hoping to find a L2E sub-query equivalent. Something like this:
[Code]....
I know LINQ to Entities does not support the " IN " clause, so I am looking for something that will work in its place.
So I have a ListView (assignmentsListView) in an UpdatePanel, being filtered by a DropDownList in the same UpdatePanel. The DropDownList has a list of persons in it and uses autopostback, and the ListView shows the tasks those persons are assigned to.
I am trying to use code similar to this:
[code]....
When I first load the page, the DropDownList shows the first person in the list, and the ListView correctly shows that persons tasks.
If I then select a person who I know has zero tasks, I get an error at the RegisterPostBackControl() method, saying the passed-in control cannot be null.
When debugging, at the RegisterPostBackControl method, it shows that the ListView Items collection has >0 elements in it (the number of elements matches the person selected before the current person).
I get this run time error "no supported translation to SQL".
What i want is to get lists of the posts, and do a small quick calculations of the rating and then sort those from highest to low and take 5 posts only.
How to use Stored Procedures with Linq to Entities? I prefer an example with input and output The videos on asp.net only show how to do this with Linq to SQL.
SELECT * FROM MessageAlerts AS A LEFT OUTER JOIN Contacts AS C ON A.ContactId = C.Id LEFT OUTER JOIN Users AS U ON A.UserId = U.Id INNER JOIN Businesses AS B ON B.Id = C.BusinessId OR B.UserId = U.Id
how to do this : ON B.Id = C.BusinessId OR B.UserId = U.Id with linq in entity framework.
WHY are all the examples on this site linq to SQL? Did ms not themselves announce dropping support for l2SQL over a year ago? i really don't get it. Examples are great.. but really not helping me since i've gone ahead and listened to MS. And can someone at MS clarify what the position is for linq 2 SQL.. Is it supported? Recommended? What the hell.
I am trying to learn LINQ to entities, and am working out how to best structure my BLL layer. I have generated the entity model and have created a generic repository in my DAL that returns results as IList<T>. I initially created the BLL to also return
results as IList<T>:
public IList<DAL.Customer> SelectAll() { [code]...
Now I am working on the aspx page, and I can create an ObjectDataSource and configure it to use my BLL, but since I am returning IList, I can't sort since I am not using a DataView. I have seen some articles on the web for converting IList to DataView, but that seems like a lot of overhead for every query.My goal is to keep a clean separation between layers without making things overly complicated. I would like to know how others have done this, or maybe a link to a good tutorial that shows how to structure all three layers.
I am building a web application in asp.Net 4.0 and entity framework. I am trying to retrieve a list of products based on a collection of id's. I first gather all the id's in a collection and then pass it to the linq query. I am trying to get a functionality similar to the IN clause in SQL. The problem seems to be with the Contains() method in the Linq to entities query. Here is my Linq code:
[Code]....
I got the above Linq to entities method from here: [URL]
I have a message table that self joins to itself where Message.ID == Message.Parent. So I have 1 Message with several ChildMessages. This is set up nicely with a Navigation property.
The code is currently:
var message = from m in soe.Messages.Include("ChildMessages") where m.ID == id && m.IsActive select m; return message.FirstOrDefault();
What I really want is to only return 1 Message (that is equal to a particular ID and isActive) with all of its Active ChildMessages and I want to do it in one call to the database.
i have a table with a field name called 'Firstname' and another field name called 'Lastname'. I would want to have a single column in my GridView which show Fullname and then the firstname and lastname are showed here under an alias. Also, i am binding my GridView using LINQ.So is there a way to create aliaswith LINQ and to use these with GridView ? Would love to have an hint about how i can realize this task.
