ADO.NET :: LINQ Entity Framework Query - Construct "nested" Query?

Jan 22, 2011

I have a web app for our golf club. When I compute handicap index for each golfer, I have to select the most recent scores and then a subset of those scores depending on how many rounds of golf the golfer has played. All the scores are entered into a single SQL Express table called "Rounds". Verbally, this is what I'm trying to do:

1) select the twenty most recent golf scores (sort on date descending, "take(20)") [if less than 20 records, then select all available];

2) for this set of records, select the 10 lowest scores (or smaller number if golfer has less than 20 rounds);

3) compute the average round differential for the subset of records, etc. to calculate handicap index (this step is working ok...)

My current VB code has this LINQ query (which is flawed -- it selects the lowest handicap differential scores of ALL records for the filtered user):

[Code]....

How do I modify this query to accomplish items 1) & 2) above? It seems this should be simple, but my experience with queries is still limited.

View 2 Replies


Similar Messages:

Entity Framework CTP5 - Code First - Nested Query Error

Jan 3, 2011

I have the following classes:

public class Category
{
public int CategoryId { get; set; }
public string Name { get; set; }
}
public partial class CategoryMap : EntityTypeConfiguration<Category>
{
public CategoryMap()
{
this.HasKey(c => c.CategoryId);
this.Property(c => c.Name).IsRequired().HasMaxLength(400);
}
}
public class MyObjectContext : DbContext
{
public MyObjectContext(string connectionStringName)
: base(connectionStringName)
{
}
public DbSet<Category> Categories { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Configurations.Add(new CategoryMap());
base.OnModelCreating(modelBuilder);
}
}

Now when I run the following code I get an exception (GenericArguments[0], 'System.Int32', on 'System.Data.Entity.Internal.Linq.ReplacementDbQueryWrapper`1[TEntity]' violates the constraint of type 'TEntity')

DbDatabase.SetInitializer<MyObjectContext>(new DropCreateDatabaseIfModelChanges<MyObjectContext>());
using (var context = new MyObjectContext("NopSqlConnection"))
{
var query1 = from c in context.Categories
select c.CategoryId;
var test1 = query1.ToList(); //works fine
var query2 = from c in context.Categories
where query1.Contains(c.CategoryId)
orderby c.Name descending
select c;
var test2 = query2.ToList(); //throws the exception
}

View 1 Replies

Show SQL Trace Of LINQ Query To Entity Framework 3.5

Oct 13, 2010

Best way to show the SQL trace of a LINQ query to Entity Framework 3.5? I am using ASP.net and EF 3.5.

Dim dbo As Web.Portal.RBMEntities = New Web.Portal.RBMEntities
Dim Query = From RoleAllocations In dbo.RoleAllocations Where RoleAllocations.user_id = _ID And RoleAllocations.expire_date > Today Select RoleAllocations

Console write the SQL trace?

View 2 Replies

ADO.NET :: Setup Query Result Shaping For LinQ To SQL Instead Of Entity Framework?

Sep 9, 2010

I am new to this, and I am trying to implement a linq query similar to db.Genres.Include("Albums") command from

mvc music store using my current DB setup. I realize that the tutorial mentions Checlking the "Include foreign key columns in the method" when creating the tables in ADO.NET, but if I am using LINQ to SQL classes, then how can I obtain the same effect. And how do I use
db.Genres.Include("Albums") to simplify my life?

View 2 Replies

C# - Unable To Construct An Entity (complex) Object From A Query

Jun 8, 2010

I am very new to entity, sql, c#, and asp.net so this might be something easily fixed. I am attempting to display all the inactive products stored in my table called products in a datagrid.

var productQuery = from b in solutionContext.Version
where b.Product.Name == search && b.Product.ActiveNumber > b.VersionNumber
select new Product
{
Name = b.Product.Name,
Description = b.Product.Description,
ID = b.ID,
LastNumber = b.Product.LastNumber,
MiddleNumber = b.Product.MiddleNumber,
RSTATE = b.RSTATE,
ActiveNumber = b.Product.ActiveNumber,
LastModified = b.Product.LastModified,
ParentID = b.Product.ParentID,
ProductType = b.Product.ProductType
};
ProductsGrid.DataSource = productQuery;
ProductsGrid.DataBind();

I am getting this error: $exception {"The entity or complex type 'SolutionsModel.Product' cannot be constructed in a LINQ to Entities query."} System.Exception {System.NotSupportedException}

View 1 Replies

ADO.NET :: Entity Framework - Query Based On Relationships?

Oct 27, 2010

I have the following related tables:

Users
Id
Username
Email
Password
UserStatuses
Id
Name
Users_UserStatus
Id
User (FK - Users: Id)
Status (FK - UserStatuses: Id)
StatusDate

As you can see, UserStatuses is a reference table with various statuses. Users_UserStatus is a join table between Users and UserStatuses. Using Entity Framework, how can I do a conditional to check if the latest StatusDate is "Pending"? As of now, I have the following:

[Code]....

View 1 Replies

ADO.NET :: [Entity Framework] Strange Error Executing A Sql Query

Nov 29, 2010

I have a strange error, I've tried to search for it before writing this post but I wasn't able to find out a solution yet.

I'm executing a query using ExecuteStoreQuery against a MySQL database, but it throws an exception reporting that there's a syntax error in my SQL.

I've tried to copy&paste the sql query into the MySQL tool and it works nicely, giving the correct results.

I've tried to open manually the connection and using CreateCommand to use it the "old way".

My query is a bit long, 4000 chars more or less, could it be the problem?

View 4 Replies

C# - Rewrite SQL Query Using Linq To Entity

Jul 12, 2010

Hi guys I need to rewrite the sql query below using Linq to entity. Unfortunately I don't have a lot of experience of using Linq.

With TempTableName AS
(SELECT [ColumnName],
[ColumnName2],
[ColumnName3],
[ColumnName4],
ROW_NUMBER() OVER (order by ColumnName desc) as RowNumber from TableName )
SELECT
[ColumnName],
[ColumnName2],
[ColumnName3],
[ColumnName4]
FROM TempTableName WHERE ROWNUMBER
Between 10 and 100

View 1 Replies

Architecture :: Ado.net Entity Framework - Query - Return Correct Data

May 26, 2010

I just tring to a complex (for me) with ado.net entity framework this is the structure: In practice it is a sort of group purchasing (Buyers) For each group of purchase (Buyer) should have the opportunity 'to select all products of the brands indicated in buyer I'm doing function to return correct data like this:

public List<Product> GetProductsByBuyer(int vBuyerId)
{
Buyersctx.Products.MergeOption = MergeOption.NoTracking;
return (from lProduct in Buyersctx.Products.Include("Brand").Include("Buyers")
where select lProduct).ToList();
}

View 2 Replies

ADO.NET :: How To Access The Grouping Resulted From A Entity Framework Query With Group

Mar 26, 2011

I'm currently learning entity framework (from the Julia Lerman book "Programming Entity Framework") and got really confused at the grouping part.

var contacts = from c in context.Contacts
group c by c.Title into myGroup
select myGroup;

This is supposed to return a Grouping<K,T> type, but the book didn't give an example on how exactly do I access this "contacts" query and I can't figure it out. When I did foreach(var contact in contacts), my "contact' variable has no knowledge of any of the properties of the Contact type (contact.FirstName etc).

View 1 Replies

Web Forms :: Entity Framework With Stored Procedure Using Defining Query

Jun 28, 2012

I wrote a defining query

 <EntitySet Name="EntityFramework" EntityType="SEOAnalysisModel.Store.EntityFramework">
<DefiningQuery>
SELECT Keyword, ResultHead ,Year from SeoAnalysis where Year = 2005

[Code].....

And this column value is repetative.

Now how can i get all column value?

View 1 Replies

DataSource Controls :: SQL Query Re-Write In Linq To Entity?

Jan 26, 2010

Need to figure out the correct way to do a simple SUM function in Linq, but also manipulate one of the feilds coming back by doing a Substring on it, here is the original SQL query:

[Code]....

View 1 Replies

Execute LINQ Query Using Properties Of Child Entity Set

Nov 25, 2010

I am having a meltdown over something that seems so simple and yet isn't working. Here's my scenario.

I have an object structure of tEvents, which contains properties of an event like a run of concerts. tEvents in turn contains an entity set of tEventOptions, which include properties like EventDate, Cancelled etc. I would like to query a list of tEvents using properties of the tEventOptions, for example filtering by date.

My pageis using a calendar object to show event dates. So I am trying to find if any tEvents in the List coming back from the database match the date of the day element being rendered in my Calendar control like so (in this snip 'data' is List and results from a db query):

[code]....

Except r, my query result var, is always true no matter what data it receives. I have tried the sub query using other properties of tEventOption and get the same 'true' result each time. I know that the data does not reflect this result so I clearly have a problem with the structure of my query, but for the life of me I cannot find a way to resolve it.

View 1 Replies

Simplify LINQ-To-Entity Query, And Make It Dynamic

Dec 4, 2010

I have this query for getting data through Entity Framework, which works today. Thing is, i want to create the query dynamically, i.e build it up in blocks, but i can't figure out how exactly to do it. I believe if i can somehow save one of the values that i retrieve in the beginning i can do it, but now i retrieve it twice (probably a bit slow as well? Unless the compiler fixes it before quering). Makes sense? Here is the LINQ:

[code]....

I.e based on if various variables have values.

View 1 Replies

Can Check Rows Returned In A QueryString Parameter Based Entity Framework Query

May 29, 2010

I need to check if any rows are returned in a QueryString here's what I have so far.not sure what code to put to see if the row count is greater than 1

private void BindDataToGrid()
{
//MessageBoardEntities3 is ThemeableAttribute connection string name
int TID = Convert.ToInt32(Request.QueryString["ThreadID"].ToString()); // if Post ID is int
var context = new MessageBoardEntities3();
gvPosts.DataSource = from p in context.Posts
where p.ThreadID == TID
select new { p.Post1, p.PostID };
gvPosts.DataBind();
lblNoPosts.Text = "No posts found for this thread.";
}

View 1 Replies

DataSource Controls :: LINQ To Entity Query - Getting Data From The RDBMS

Jan 1, 2010

if LINQ to Entity queries the EDMX class or its .CSDL or SSDL XML on its way to getting data from the RDBMS?

View 8 Replies

Forms Data Controls :: Sql To Linq Query / Looking To Translate An SQL Query Into Linq?

May 28, 2010

I'm looking to translate an SQL query into linq

INNER JOIN Usrs ON
SAQ.UserId =
Usrs.UserId AND Scan.UserId =
Users.UserId

I'm not sure how to include the "AND" in the LINQ statement.

View 3 Replies

DataSource Controls :: Accessing FK From A Query Via Entity Query

Jan 21, 2010

I've got a query such as

Dim MediaQuery =
From m
In dB.DOWNLOADS _Where m.ID = id _Select

which returns a record from the database. One of the fields in the record is a FK to another table. I need to read this value to be able to set a dropdown based on the ID but I can't work out how to access it. For a standard record I can just do the following txtTitle.Text = MediaQuery.FirstOrDefault().TITLE

However with the foreign key it doesn't work like that. I've tried drpGroup.SelectedIndex = MediaQuery.FirstOrDefault().DOWNLOAD_GROUPS.ID where DOWNLOAD_GROUPS is the FK field but it returns Object reference not set to an instance of an object. If you're simply wanting to read some values from a single db record in the entitiy framework and one is a foreign key how should I go about getting the value?

View 2 Replies

DataSource Controls :: How To Convert Sql Query Into Linq Query

Mar 10, 2010

select Groupid,GroupName,onorusername from palgroup where groupid in (select distinct Groupid

View 5 Replies

Access The Group Of A Linq Group - By Query From A Nested Repeater Control?

Mar 26, 2010

I'm using a linq group by query (with two grouping parameters) and would like to use the resulting data in a nested repeater.

var dateGroups = from row in data.AsEnumerable()
group row by new { StartDate = row["StartDate"], EndDate = row["EndDate"] };
"data" is a DataTable from an SqlDataAdapter-filled DataSet. "dateGroups" is used in the parent repeater, and I can access the group keys using Eval("key.StartDate") and Eval("key.EndDate").

Since dateGroups actually contains all the data rows grouped neatly by Start/End date, I'd like to access those rows to display the data in a child repeater. To what would I set the child repeater's DataSource? I have tried every expression in markup I could think of; I think the problem is that I'm trying to access an anonymous member (and I don't know how.) In case it doesn't turn out to be obvious, what would be the expression to access the elements in each iteration of the child repeater? Is there an expression that would let me set the DataSource in the markup, or will it have to be in the codebehind on some event in the parent repeater?

View 3 Replies

Linq Query Returning Less Records Than Sql Query?

Mar 19, 2011

I am facing a big problem with simple linq query.. I am using EF 4.0..

I am trying to take all the records from a table using a linq query:

var result = context.tablename.select(x=>x);

This results in less rows than the normal sql query which is select * from tablename;

This table has more than 5 tables as child objects (foreign key relations: one to one and one to many etc)..

This result variable after executing that linq statement returns records with all child object values without doing a include statement.. I don't know is it a default behavior of EF 4.0 . I tried this statement in linqpad also..but there is no use... But interesting thing is if I do a join on the same table with another one table is working same is sql inner join and count is same..but I don't know why is it acting differently with that table only.. Is it doing inner joins with all child tables before returning the all records of that parent table?

View 2 Replies

Linq Query - How To Select Inner Query Into List

Oct 17, 2010

I am writing a linq query to select a blogpost,

[code]....

The blogpost i am testing got 3 tags attached to it. The table structure is:

(table)BlogPost -> (table)BlogPostTags <- (table)Tags

So the BlogPostTags table only contains 2 fields, BlogPostID and TagID.

When i run the query above i get 3 results back. Same blogpost 3 times but with 1 tag in each. It should return 1 post with 3 tags. The problem lies in the Tags query above.

View 1 Replies

ADO.NET :: Dynamic LINQ Query / Use "if Statement" In Linq Query

Feb 11, 2011

I want to use "if statement" in Linq query. How can I do this situation?

For example:

if txtAge.Text=="", I will not use that in Linq Query.

else txtAge.Text!="", I will use that in Linq Query.

View 8 Replies

C# - Loading A Nested Repeater With Data From 2 Entity Framework Queries?

Jan 20, 2010

I have 2 tables A and B that have a many to many relationship. I am using nested repeaters to show the data in a web page. My issue is, how do I write an ObjectQuery or an IQueryable query that returns the parent rows in A and the child rows in B so that I can use them as my data sources for my inner and out repeater. I have the code I wrote so far below but I am not sure if it is correct or even close.

<asp:Repeater ID="A" runat="server"><br/>
<ItemTemplate><br/>
<h2 class="Information"><br/>

[code]...

View 1 Replies

ADO.NET :: Entity Framework Vs LINQ To SQL

Mar 21, 2011

Whats the best method to use with MVC? Entity Framework or LINQ to SQL?

View 4 Replies







Copyrights 2005-15 www.BigResource.com, All rights reserved