i'm having a little problem in my project. i'm using ADO.Net Entity Data Model, let's say i have 2 Tables:
Offices : a. id
b. Name
Requests: a. rid
b.fname
c.lname
d.mobile
i want the requests table will have a relations to the offices table that each row in requests will have the id of the one of the tables. i tried to do 1 to many relations but it didn't work , i just couldnt add data to the table.
How can I share the auto-generated entity data model (generated object classes) amongst all layers of my C# web app whilst only granting query access in the data layer? This uses the typical 3 layer approach: data, business, presentation.
My data layer returns an IEnumerable<T> to my business layer, but I cannot return type T to the presentation layer because I do not want the presentation layer to know of the existence of the data layer - which is where the entity framework auto-generated my classes.
It was recommended to have a seperate layer with just the data model, but I'm unsure how to seperate the data model from the query functionality the entity framework provides.
when i create my entity data model i have a situation in the DB like this :
TableFirst : [Id,IdTableSecond,IdTableSecondAgain];TableSecond[Id]
Created data model is: TableFirst.TableSecond and TableFirst.TableSecond1
Question is: Every time when i create my entity TableFirst.TableSecond will have same relation in behind (IdTableSecond) and TableFirst.TableSecond1 (IdTableSecondAgain)
or they may change?
my application have two tables. TableA and TableB TableA have one record
ID StudentName Age
1 MARK 20
I use selectlist to select StudentName .
ViewData["StudentName"] = new SelectList(_db.StudentSet.ToList(), "StudentName", "StudentName");
and then add to TableB. for this case , for me is success, but I also want to add the"Age" into TableB on same time. I don't know how to do it.
I developed and entity framework (.edmx) application in 4.0 in that i got all the data of my querying table and its foreign key referenced tables data also. but when i change my project to 3.5 i am unable to get the data of foreign key referenced tables data.
View 2 RepliesI am new to Entity Framework and working my way through it little by little. I think I have it figured out on how to get data into and out of 1 table at a time now the challenge is 2 tables into a gridview.
I have a user table that has a list of threads that a user can mark to track. Easy enough. Assign the userid number & threadid to a table with a push button while the user is logged in and viewing any of the posts that are on that thread. The new challange is to get only the posts that the user has marked to track. SQL easy. Entity not sure what to do.
If I make a view or stored procedure and add it to the database that would be an extra step. To join the 2 tables as in sql Select posts from posts where track.userid = @userid join track on post.userid=track.userid Seems Entity was made to avoid this type of thing. Than once the data is gathered I need to bind it to a gridview()
Adding data into kartlar table (RehberID,KampanyaID,BrimID) is ok. But which Kart'ID created? I need to learn which Id created after adding data (RehberID,KampanyaID,BrimID) into Kartlar?
[code]...
How can I do that? I want to get data from Kartlar which data I added?
when i create ado.net entity data model and I add two tables only one is added to entity data model
none of the tables have any kind of relationship are simple tables.
I have 3 tables. I need to insert data from 2 tables into the 3rd table.
The first table has 2 fields -- c_id, c_key
The second table has -- t_id, u_id, partial_c_key
I need to insert c_id, u_id in the 3rd table.
Problem is partial_c_key in the second table contains only a part of the c_key in the first table.
Ex:
First table:
c_id--c_key
1--200A
2--200B
3--200C
4--301A
Second Table:
t_id -- u_id -- partial_c_key
1--23--200
2--36--301
In the data above partial_c_key 200 has 3 c_ids in the first table (1,2,3 with values 200A, 200B, 200C) and 301 has just 1 which is 301A.
In the 3rd table I need to insert c_id, u_id so the data should be
u_id -- c_id
23 -- 1
23 -- 2
23 -- 3
36 -- 4
How do I write a query to accomplish that?
I am new to Linq to Sql. I was wondering if there was a way that I could override the default naming convention on the tables in the .DBML file. I am asking because the person who designed the database I am using prefaced all of the table names with DGIS_. For instance, my customer table is called DGIS_Customers. I would prefer that the classes in the DBML file be called Customer, not DGIS_Customer.
View 3 Repliesi have the following code where I want to retreive the data form a table using entity framework and put it to a list of the same type:
List<ItemDetail> iDets = new List<ItemDetail>();
iDets = (List<ItemDetail>) from l in db.ItemDetails
where l.ItemID == varItemID
select l;
when I run the page, it throws the following error:
Unable to cast object of type 'System.Data.Objects.ObjectQuery`1[LIBRIModel.ItemDetail]' to type 'System.Collections.Generic.List`1[LIBRIModel.ItemDetail]'.
why i'm having this problem? or am I missing something here if i'm not wrong it worked once, but now it throws this error
I have two tabels as mentioned below. I am using entity framework and vs2010.I am not able to write linq query to get data from both the tables. there is one to many relationship(for one category ther can be multiple articles).
View 1 RepliesI need to dynamically access some SQL tables hopefully using the Entity Framework. Here's some pseudo code:
var Account = DB.Accounts.SingleOrDefault(x => x.ID == 12345);
which will return me an Account object and this contains some fields called "PREFIX", "CAMPAIGN ID" and further information about the accounts are stored in separate SQL tables with the naming convention of PREFIX_CAMPAIGNID_MAIN.
The tables all have the same fields so I was thinking of creating a new Entity that isn't mapped anywhere and then dynamically loading it, like so:
var STA01_MAIN = new MyAccount(); // my "un-mapped" entity
DB.LoadTable('STA01_MAIN').LoadInto(STA01_MAIN);
I can now get anything about the STA01_MAIN account: STA01_MAIN.AccountId. So my question is: how do I access these tables using the Entity Framework?
I'm a newbie to this so bear with me. From what I've read online LINQ to Entity should see the relationships without having to specify the joins between multiple tables. I have a relationship that goes across 4 tables Employee, EmployeeDepartmentLink, EmployeeProjectLink, and Project. The idea is an employee can be in multiple departments and work on multiple projects with it being specified which department the employee is in for that project.
This is a C# MVC3 program connecting to a SQL database using VS 2010 Express.
I have no problem with running this query to find employees on a project:
[Code]....
Tring to do the reverse, finding projects that an employee worked on results in an error:
[Code]....
Error message: The specified type member 'EmployeeDepartmentLinks' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported. So I have 2 questions,
1) Why would it work in one direction and not the other? I've played around with it for a couple days with the same results.
2) Does it matter that my primary key and foreign keys are not named the same since all the relationships are connected in SQL? Ex: in Employee (EmployeePK)--(EmployeeFK) in EmployeeDepartmentLink Trying different stuff in LINQPad I was able to get the 2nd query to work if I specified all the joins which I thought was not neccesary with LINQ to Entity. I converted an SQL query that I made on the server into a LINQ query below which works.
I have a question about Entity Framework. answer if you know answer on this. I have such query :
[Code]....
Particularly I want to join few tables in one query, but I can NOT use LINQ and can NOT use ObjectQuery with objects mapped to DB fields inside my query. Because each entity creates dynamically. So this is what i
can NOT use : [URL]
The question is can I use something like this instead of using objects?
[Code]....
The purpose is to use Join method of ObjectQuery with syntax as in Where method :[URL]
A relative newcomer to .net MVC2 and the entity framework, I am working on a project which requires a single web application, (C# .net 4), to connect to multiple different databases depending on the route of access, (ie subdomain).
No problem with this in principle and all the logic is written to transform the subdomain into an entity connection and pass this through to the Entity Model.
The problem comes with the fact that the different database whilst being largely similar in structure contain 3 or 4 unique tables bespoke to that instance.
To my mind there are two ways to solve this issue, neither of which i am sure will be possible.
1/ Use a separate entity model for each database. -Attempts down this route have through up conflicts where table/sp names are the same across differnt db's, or implicit conversion errors when I try and put the different models in different namespaces. or
2/ Overwrite the classes which refer to the changeable database objects based on the value of a base controller property.
My question is if either of theser routes can ever work in principle or if i should just give up on the EF and connect to the dtabases directlky using ADO. Perhaps there is another way to solve this problem i haven't thought of?
i have 3 tables which are Table A(a Id,b Id),
Table B(b Id,a Id,c Id),
Table C(c Id,b Id)
How can i select Table C column by using table A?
i have dataset with two data tables inside
dt1
dt2
i want to bind data from both data table t gridview
for this how can i make join between two data tables inside dataset and retreive data
When adding a stored procedure into the Entity Data Model I can select whether the procedure returns a scalar, a (new) complex type or one of the entity types I already defined.I mean assuming I have a view like this
CREATE VIEW FilteredFoos as SELECT Foo.* FROM Foo join ... WHERE ...(that is a view that implements some involved filtering, but returns all columns from one table) how do I add it to the project so that I can use the entity set, but get the Foo objects, not some new FilteredFoo objects.
var foos = myDB.FilteredFoos.Include("Bar").ToList();
foreach (Foo foo in foos) { ...
I have created a .edmx for the northwind database. When I run the following statement, the correct number of detail records are retrieved and I can access the detail fields, but how do I access the order header record to view OrderDate, ShipAddress, etc...?
[Code]....
I am working with VS 2010, Entity framework, SQl-Server 2005, ASP.Net web forms. Currently, I am working on the Data access layer library which soon will be a web service, using Entity Framework collaboration with different design patterns like repository pattern and some best practices that posts in different blogs. I am also test each repository using the Unit testing project. Thumbs up! Working fine.
The thing I am worried about is, how much is good for retrieving data from a table that can contain 80-100k records ?
I need a code to share a patients records in image and table content in e-mail among doctors group.
View 1 RepliesUsing a very run-of-the-mill database, with identity int for primary keys, a Dynamic Data Entities Project (EntityFramework) displays the primary key for view and edit. When using Linq to Sql, the primary key fields are not displayed.
I would like to hide the primary keys and use Entity Framework (VS 2008, .Net 3.5 sp1).
I'm working on a new project where I have the luxury of working from a Model to Database approach using Entity Framework 4.
The project I'm working on is taking an agile approach where different phases will be rolled out over time.
Will the Model First approach work in my case? I noticed when you "Generate Database from Model" it recreates the entire schema from scratch which will obviously wipe all the data that is in the db. I was hoping for a more "Update Database from Model" approach where the db would just be altered to reflect the changes rather than recreated
My dataset table data is from multiple tables (showing on a gridview),How to update the database tables using batch udpate on clicking submit, if the data is from a signle table, no problem, but I am not sure how to handle if the datais from mulitiple tables? If I have related tables, do I need put them in differet tables in the dataset?
View 6 Replies
