I want to create a LINQ DataContext Class as per Database Design. I getting a problem in some cases.
the syntax to bulid a LINQ class :
[Code]....
Here Table Name Is HardCoded But I my case my Table Name A Changed as Finicial Year Change.So How I Give The TableName As RunTime
I have a linq DataSource and a Grid in my htnl and I want to access the DataContext from code behind. Now in the past when I do evrything in code behind I just use...
DataContextName db = new DataContextName();
and I have my reference.
Now I can still do that and it works fine it just seems odd to be making a second class object when there is one that is made from the linq DataSource in the html. But I can't figure out how to get a reference to the DataContext that is created from my html code.
I'm studing Linq on TheBeerHouse Project,I would create a my Linq Version.I have a big problem with Updating, this i a part of source :
protected static ArticlesDataContext GetContext()
{
return new ArticlesDataContext(Settings.ConnectionString);
[code]...
I have a strange problem. I am adding a LinqDatasource object, and set the context:
[Code]....
Then I get this error:The type 'System.Data.Linq.DataContext' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Data.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.
On web.config I already have this:
<add assembly="System.Data.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
NOTE: The datacontext is in a different project (DLL proect) where I added a refernce to System.Data.Linq.
is there another way adding a refernce to a web project? or only though teh web.config?
cannot create datacontext for make a select
View 2 RepliesI am building a page that displays a product's details, with the information being called from an MSSQL database.I would like to be able to have a variable number of features listed for each product, so for example, Product A has a list of 3 features, Product B has a list of 7 features, Product C has 2 features listed etc.I would like to avoid having a lot of NULLS in my database, and would prefer not to restrict the number of possible features listed.Is there a common way to tackle this problem? Is it simply a case of setting up a table just to store features?
View 2 RepliesI am new to LINQ but not >net. I do understand SQLDataSource, etc. I was just told by a coworker not to use a LINQ to SQL Class for my new project (Bank.dbml). I was told to use instead the ADO.Net Entity Data Model (bank.edmx).
BankModel.edmxBank.dbml
When only using ADO.Net Entity Data Model I try to associate a GridView with a new LinqDataSource I get no options. When I add a LINQ to SQL Class I get the option to use it but it is empty. Is this because all my LINQ classes are mapped in the ADO.Net Entity Data Model (bank.edmx)? Can someone tell me (or point me to) what the differences are in these two?
everytime I modify an SQLdatasource using VS wizards, I have to dettach the mdf in VS's server exporer, then hit refresh in the browser, then get the applicaiton is offline error message please remove some pia file, but i usually just count to 12 and then hit refresh again and the page renders properlyhad scoured the forum on more than one ocasstiion, think it has something to do with the Admin rights within SQL, Ive tried the SQL server surface configuration tool, and add administrator stuff, but not sure if i should add (user to provision) something like the asp.net thing, or network services or ??also cant figure out where to view which administrators are actually on SQL server,
View 4 RepliesI'm trying to use linq to sql for my project (very short deadline), and I'm kind of in a bind. I don't know the best way to have a data context handy per request thread. I want something like a singleton class from which all my repository classes can access the current data context. However, singleton class is static and is not thread-safe and therefore not suitable for web apps. I want something that would create a data context at the beginning of the request and dispose of it along with the request
View 1 RepliesIn general terms, which way will require more server processing power and which way will return faster queries... if there is even a difference. The client's database is still on the dev MS SQL server but is essentially but the client has decided they want to collect two more fields of information. Both fields are going to be collection text data and probably varchar(300) will be sufficient for the column data types. Would it ultimately be more efficient to
Add two additional columns in the main table so the data is entered directly into each record, or Add an additional table (or two) with a foriegn key to the primary table that holds the info for each new field The SELECT statement for the main table could be modified to either add the new columns (a.NewColumn1 and a.NewColumn2) or it could contain nested SELECT statements that pull in the data from the other tables. Custom daisy-chained Insert or Update statements would be no problem and a cascade Delete relationship would take care of any deletions. I'm just trying to figure out which would be better from a performance standpoint?
Not sure if this is for SQL or .net! I have 3 tables which looks like
table1
ID Name
1 Jon
and
table2
ID Number Job
1 1 IT
2 1 Web
3 1 Admin
table1
ID ContractType
1 Temp
1 Perm
An inner join makes one table with 3 rows (I excluding the ID from table 2 for the join) which is saved as a view
viewTable
ID Name Number Job ContractType
1 Jon 1 IT Temp
2 Jon 1 Web Temp
3 Jon 1 Admin Temp
4 Jon 1 IT Perm
5 Jon 1 Web Perm
6 Jon 1 Admin Perm
I want to display these results on a web page via the grid view. However, I don't want to show the user 6 times! I want to show the user name once, the contract type once and each Job! What is the best way to do this? Is there a fault with the database design already? I assume the easiest answer is to not join them in a view but query each section 3 times from the website but I'd rather 1 connection only!
For no apparent reason (of course there must be one), my web project will no longer generate LINQ to SQL classes/data contexts!!!I am going about the usual routine of right clicking the project, adding new item, selected LINQ to SQL classes, then dragging over a table from Server Explorer, saving and build but no...the bloody thing won't appear!!!Does anyone know why this might be happening/what have I done wrong?
View 1 RepliesI have a problem. (this a simplfied example)
In Entity framework I have a class which is effectively
fooEntity
{
public Guid Id {get; set;}
and a collection of fooChildEntity
}
a fooChildEntity is again an entityframework class
fooChildEntity
{
public Guid kidId {get; set;}
}
Now I also have a pair of business layer classes foo and fooChild
foo
{
public Guid Id {get; set;}
ilist<fooChild> Children {get;set;}
}
fooChild
{
public Guid kidId {get; set;}
}
My aim is to write a linq to entites that will allow me to convert the entity foo and children into the business foo and children without breaking deferred execution ( I will be adding filters to reduce the recordset at a higher coding level in the business layer)
doing something like
this.context.fooEntity
.include(fooChildEntity)
.Select( fe => new foo { Id=fe.Id ,
fe.foreach(fec => Children.add( new fooChild { kidId = fec.kidId}))})
.AsIQueryable()
is plainly rubbish and would never compile - it is however an indication of the direction I was thinking .
Even if I got a foreach to work like that or similar it would break deferred execution
At this point there are around 300,000 foo entities which I will eventualy filter to 5 or 6 foo's - this is why deferred execution is needed.
I am trying to create linq from A list:
[Code]....
But I always get this error:
[Code]....
I'm using this class to do search:[URL]
I have 2 databases one called DB1, and the other DB2. Both of them has exactly the same design (tables, procedures and etc..)
Now, I am using SQLMETAL to create the DataContext. problem is that there are two lines that direct to a certain database and so I cannot use the same code for both databases.
here is the code:
[Code]....
Now, What I am lookin for is a programmatically way to change this two lines (DataBaseAttribute and the connrection string) .
The easiest solution for me of course is to create the class twice, with the same code and just change manually what I need which is not what I am looking for.
There is a full discussion with microsoft stuff right here: [URL]
string connectionString = (string)
ConfigurationSettings.AppSettings["ConnectionString"];
SqlConnection connection = new SqlConnection(connectionString);
SqlCommand command = new SqlCommand("INSERT_PERSON",connection);
command.CommandType = CommandType.StoredProcedure;
command.Parameters.Add(new SqlParameter("@Name",SqlDbType.NVarChar,50));
command.Parameters["@Name"].Value = txtName.Text;
command.Parameters.Add(new SqlParameter("@Age",SqlDbType.NVarChar,10));
command.Parameters["@Age"].Value = txtAge.Text;
connection.Open();
command.ExecuteNonQuery();
connection.Close();
Above is my code.
I has more than 100 methods like this, so every time i'm opening the connection and close it, this will take too much of time, what i think is instead of this i would like to create the class for Connection open, that class will check whether the connection is closed or Broken then Open it(like SqlHelper.cs) so without big change on my methods, how to create that class and how to access that class from my methods.
i am working on Linq,as we know to use any table in linq we have to drag and drop it on our datacontext's Designer File,and at run time we got its value,till here no any problem,main point is if any changes in respective data source's schema has made ,then on datacontext we will not get that changes,for it we have to change this datacontext manually by by again drag and drop,it will not happen implicitly when this changes has been made on the data source. how i solve this problem so that datacontext change implicitly without any over head using .net 3.5.
View 2 RepliesSystem.Data.Linq.ChangeConflictException: 2 of X updates failed. at System.Data.Linq.ChangeProcessor.SubmitChanges(ConflictMode failureMode) at System.Data.Linq.DataContext.SubmitChanges(ConflictMode failureMode) at PROJECT.Controllers.HomeController.ClickProc(Int32
id, String code, String n)
This is what I get very often. This action is done thousands of times a day, and I get this exception about once every 5 seconds. From what I understand it happens when something changes in the database in the period between creating DataContext and updating it. Am I right?How can I fix it?I just debugged the error and found the following:
[Code]....
The Stats table is updated constantly. So how can I still make LINQsave the changes. With "classical" MS SQL access through SqlDataCommand I never had problems like that.
I am trying to return all records from a table using a Linq strongly typed datacontext. I want this in its own dll and accessible via a public method. I am basing this on the following MSDN example:
[URL]
I get no intellisense for appt in the Linq code and I also get a compile error for Table<Appointments>:
The type or namespace name 'Appointments' could not be found (are you missing a using directive or an assembly reference?)
Here is my code:
[Code]....
i want create a class Library work with SQL Linq ,when i create a LINQ Data Class it automatic create some connectionString and use the database namemy question is can i change some settings that, use this class Library in difrent website with difrent connectionStrings?
View 6 RepliesI am writing an application in C# that uses LINQ to validate a datacontext off a textbox to see if the record exists already. If the record does exist I inserted an if statement to advise the user that the record exists, if the record does not exist I would like to allow the record to be added to the database. If I take out my else statement everything works fine as far as inserting goes, but I do not want to allow inserts in this scenario. I have tried moving the if and else statement to different parts of the code but can't quite figure this one out.
[Code]....
I need my linq to sql datacontext to be available across my business/data layer for all my repository objects to access. However since this is a web app, I want to create and destroy it per request. I'm wondering if having a singleton class that can lazily create and attach the datacontext to current HttpContext would work. My question is: would the datacontext get disposed automatically when the request ends? Below is the code for what I'm thinking. Would this accomplish my purpose: have a thread-safe datacontext instance that is lazily available and is automatically disposed when the request ends?
public class SingletonDC
{
public static NorthwindDataContext Default
{
get
{
NorthwindDataContext defaultInstance = (NorthwindDataContext)System.Web.HttpContext.Current.Items["datacontext"];
if (defaultInstance == null)
{
defaultInstance = new NorthwindDataContext();
System.Web.HttpContext.Current.Items.Add("datacontext", defaultInstance);
}
return defaultInstance;
}
}
}
I'm new to LINQ and have a problem with my query not showing me the Table Collection. I manually created my Cart class and specified the table attributes on each property (works fine for inserting records via LINQ see below). DataContext dc = new DataContext(Conn);
var q = (from c in dc.NOTABLES?? where ((c.UserID == userID)) orderby c.CreateDateTime Based on examples I would expect to see dc.Cart But I don't, so I tried to access it via dc.GetTable<Cart>() which at least gets me data but doesn't seem to convert the rows to my Cart object since this:
foreach (var cart in q) Log.Info("UserID: " + cart.UserID + " CartID: " + cart.ID.ToString());
blows up with a "Specified Cast is Not Valid" exception.
No Problem Inserting Also, I had no problem inserting data into the database:
DataContext dc = new DataContext(Conn);
Table<Cart> Carts = dc.GetTable<Cart>();
Cart aCart = new Cart();
aCart.UserID = userId;
aCart.Description = description;
aCart.CreateDateTime = System.DateTime.Now;
aCart.UpdateDateTime = System.DateTime.Now;
Carts.InsertOnSubmit(aCart);
Carts.Context.SubmitChanges();
I am trying to run a linq query but I need the result as a datatable as I am using that to store records from different queries in the same viewstate object.The 2 versions below compile, but return an empty set. The exact error is "Value cannot be null.Parameter name: source". (and yes I have checked there is data):
MyDatabaseDataContext db = new MyDatabaseDataContext(conn);
IEnumerable<DataRow> queryProjects =
(from DataRow p in db.STREAM_PROJECTs.AsEnumerable()
[code]...
my query is SELECT a.HD, a.HEAD, a.SH, a.SUBHEAD, a.TRK, a.TRACK, a.TGT, a.TARGET, a.PDC, a.DT_RELEASE, a.STATUS, a.CO
FROM V_HIERARCHY1 a
my data is ,HR HR Rec Records Leave Leave Records HRL.0001 Policy and Process for leave record. 27.06.2010 30.06.2010 WIP Edlink
HR HR Rec Records Leave Leave Records HRL.0002 Quarterly Review 01.07.2010 04.07.2010 Planned Edlink
HR HR DB Database SAL Salary DDS.0001 Calculation of Monthly salary 08.08.2010 09.08.2010 WIP Edlink
HR HR Rec Records Ind Induction Records HRI.0001 Completion of dossiers. 08.07.2010 10.07.2010 WIP Edlink
HR HR DB Database Emp Employee HDE.0001 Offer letter 06.07.2010 09.07.2010 WIP Edlink
my outout is ,HR
REC
LEAVE
HR1
REC1
LEAVE1