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?
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Apr 23, 2010
As the title sugests, I am missing a (basic?) concept as I teach myself asp.net, linq, and C#. It has been awhile since I've done anything object oriented, so I don't know how much that is impacting this gap in my understanding. Anyhow, here is what I am trying to do. I have three SQL Server tables: PERSON, POSITION, AREA. There is a 1 to many relationship between PERSON and POSITION, and a 1 to 1 relationship between POSITION and AREA. Given the following code I verify who the person is who has logged into the browser:
[Code]....
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Jan 1, 2010
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Jun 16, 2010
I have a button click event that adds a record to a table based on the userid and threadid the user is viewing. I am a bit new to entity so I am stumbling around. I have to where conditions
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Sequence contains no elements
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Mar 9, 2011
I have a user control, named productslist.ascx. On pruductslist.ascx, I am using Entity Datasource and a QUERY EXTENDER and LISTview. I have a page Defualt.aspx. On Defualt.aspx, I have a TEXTBOX with a SUBMIT button for searching the site. Everthing works fine so far, AS LONG as the results of the Search is posted back to Default.aspx. What I want is for the results of the search to be posted on a different page.
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Aug 22, 2010
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Jan 15, 2010
[code]...
This query works perfectly on the query analyser.
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[Code]....
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Jul 13, 2010
I'm encountering a strange problem. Here is the scenario. I have built a query that accepts a parameter (WHERE LIKE clause).
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Mar 28, 2011
Dim p = From i In context.persons
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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
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Oct 27, 2010
I have the following related tables:
Users
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Username
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Id
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[Code]....
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Nov 25, 2010
I am having a meltdown over something that seems so simple and yet isn't working. Here's my scenario.
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[code]....
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[code]....
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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.
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Nov 6, 2010
I can't seem to figure out how to write this query properly. I've tried various combinations but nothing's worked yet. Below is the relevant portion of my database model: I need to select the products that match a given Category and Group, and that match a given Year, Make, Model, submodel. This I've done below:
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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
};
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ProductsGrid.DataBind();
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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?
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Aug 1, 2010
I'm having a hard time really grasping this concept. I've done a lot of development with Microsoft Access, so I'm very familiar with the structure of tables, queries, and all that sort of thing. And maybe that's really hindering me with understanding what to do with ASP.NET/VB.NET development.
I have an ASP.NET web application, and I want to pull a UserName and the date that this user was created and last logged on. UserName is in the ASPNETDB's aspnet_Users table, and date created and last logged on is in the membership table. So in database explorer in Visual Web Developer, I opted to create a "New Query". It brought up the UI and I selected these two tables. Linked them with the primary key of UserID. Then I selected the three necessary fields (UserName, date created, and last logon date). Looks good, viewed the data. But there is no way to save this query to programatically reference it. I want to see what user is logged on, and then look through this query to get the other two pieces of data. But there is no way to save/reference this query.
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Apr 21, 2010
I am using Querystring "ddl4" to pass on value of a drop down list to the next page where I am using that value in the WHERE clause of a SQL command. I also need to check whether ddl4 is blank or not which I do using If Else in SQL command. I am not able to run the query where the Querystring ddl4 IS NULL
This is the sample link with the Querystring ddl4 carrying a blank value:
[code]....
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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
}
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