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  • How can i query for null values in entity framework?

    - by AZ
    I want to execute a query like this var result = from entry in table where entry.something == null select entry; and get an IS NULL generated. Edited: After the first two answers i feel the need to clarify that I'm using Entity Framework and not Linq to SQL. The object.Equals() method does not seem to work in EF. Edit no.2: The above query works as intended. It correctly generates IS NULL. My production code however was var value = null; var result = from entry in table where entry.something == value select entry; and the generated SQL was something = @p; @p = NULL. It seems that EF correctly translates the constant expression but if a variable is involved it treats it just like a normal comparison. Makes sense actually. I'll close this question

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  • Specification of Extended Properties in OleDb connection string?

    - by Monty
    At the moment I'm searching for properties for a connection string, which can be used to connect to an Excel file in readonly mode. Searching Google gets me a lot of examples of connection strings, but I can't seem to find a specification of all possibilities in the 'Extended Properties' section of the OleDb connection string. At the moment I've this: Provider = Microsoft.Jet.OLEDB.4.0; Data Source = D:\Data\Customers.xls; Extended Properties = 'Excel 8.0; Mode=Read; ReadOnly=true; HDR=Yes'; However... I've composed this by examples. So questions: 1. What is a decent source for OleDb Connection String documentation/reference? 2. Is the above connection string indeed connecting to the Excel file in readonly mode? Thanks!

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  • Updating a Data Source with a Dataset

    - by Paul
    Hi, I need advice. I have asp.net web service and winforms client app. Client call this web method and get dataset. 1. [WebMethod] 2. public DataSet GetSecureDataSet(string id) 3. { 4. 5. 6. SqlConnection conn = null; 7. SqlDataAdapter da = null; 8. DataSet ds; 9. try 10. { 11. 12. string sql = "SELECT * FROM Tab1"; 13. 14. string connStr = WebConfigurationManager.ConnectionStrings["Employees"].ConnectionString; 15. 16. conn = new SqlConnection(connStr); 17. conn.Open(); 18. 19. da = new SqlDataAdapter(sql, conn); 20. 21. ds = new DataSet(); 22. da.Fill(ds, "Tab1"); 23. 24. return ds; 25. } 26. catch (Exception ex) 27. { 28. throw ex; 29. } 30. finally 31. { 32. if (conn != null) 33. conn.Close(); 34. if (da != null) 35. da.Dispose(); 36. } 37. } After he finish work he call this update web method. He can add, delete and edit rows in table in dataset. [WebMethod] public bool SecureUpdateDataSet(DataSet ds) { SqlConnection conn = null; SqlDataAdapter da = null; SqlCommand cmd = null; try { DataTable delRows = ds.Tables[0].GetChanges(DataRowState.Deleted); DataTable addRows = ds.Tables[0].GetChanges(DataRowState.Added); DataTable editRows = ds.Tables[0].GetChanges(DataRowState.Modified); string sql = "UPDATE * FROM Tab1"; string connStr = WebConfigurationManager.ConnectionStrings["Employees"].ConnectionString; conn = new SqlConnection(connStr); conn.Open(); cmd = new SqlCommand(sql, conn); da = new SqlDataAdapter(sql, conn); if (addRows != null) { da.Update(addRows); } if (delRows != null) { da.Update(delRows); } if (editRows != null) { da.Update(editRows); } return true; } catch (Exception ex) { throw ex; } finally { if (conn != null) conn.Close(); if (da != null) da.Dispose(); } } Code on client side 1. //on client side is dataset bind to datagridview 2. Dataset ds = proxy.GetSecureDataSet(""); 3. ds.AcceptChanges(); 4. 5. //edit dataset 6. 7. 8. //get changes 9. DataSet editDataset = ds.GetChanges(); 10. 11. //call update webmethod 12. proxy.SecureUpdateDataSet(editDataSet) But it finish with this error : System.Web.Services.Protocols.SoapException: Server was unable to process request. --- System.InvalidOperationException: Update requires a valid UpdateCommand when passed DataRow collection with modified rows. at WebService.Service.SecureUpdateDataSet(DataSet ds) in D:\Diploma.Work\WebService\Service1.asmx.cs:line 489 Problem is with SQL Commad, client can add, delete and insert row, how can write a corect SQL command.... any advice please? Thank you

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  • How can i return IEnumarable data from function in GridView with Entity FrameWork?

    - by programmerist
    protected IEnumerable GetPersonalsData() { // List personel; using (FirmaEntities firmactx = new FirmaEntities()) { var personeldata = (from p in firmactx.Personals select new { p.ID, p.Name, p.SurName }); return personeldata.AsEnumerable(); } } i wan to send GetPersonelData() into GridView DataSource. Like That: gwPersonel.DataSource = GetPersonelData(); gwPersonel.DataBind(); it monitored to me on : gwPersonel.DataBind(); this error: "The ObjectContext instance has been disposed and can no longer be used for operations that require a connection."

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  • how to get group total in self refrenced data in data table ?

    - by Nikhil Vaghela
    I have three columns in my data table. 1) ProductID 2) ProductParentID 3) ProductTotal ProductID and ProductParentID are self refrencing columns where i can set parent child relationship and get child rows based on my relationship. Let us say i have following data Product1     Product11     Product12     Product13         Product131         Product132         Product133 Product2     Product21     Product22     Product23 Next to above hierarchy in Product total column what i want is total of each child rows and sum of those child rows product total should be rolled up to it parent product. E.g if Product 131 total is 10,Product 13 total is 15 and Product 133 total is 5 then the product 13 total should be 30. The logic should work for n number of self hierarchy. Is there any functionality in data table itself where i can achieve this without iterating through each row and do it manually ? Thanks.

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  • Using LinqExtender to make OData feed fails

    - by BurningIce
    A pretty simple question, has anyone here tried to make a OData feed based on a IQueryable created with LinqExtender? I have created a simple Linq-provider that supports Where, Select, OrderBy and Take and wanted to expose it as an OData Feed. I keep getting an error though, and the Exception is a NullReference with the following StackTrace at System.Data.Services.Serializers.Serializer.GetObjectKey(Object resource, IDataServiceProvider provider, String containerName) at System.Data.Services.Serializers.Serializer.GetUri(Object resource, IDataServiceProvider provider, ResourceContainer container, Uri absoluteServiceUri) at System.Data.Services.Serializers.SyndicationSerializer.WriteEntryElement(IExpandedResult expanded, Object element, Type expectedType, Uri absoluteUri, String relativeUri, SyndicationItem target) at System.Data.Services.Serializers.SyndicationSerializer.<DeferredFeedItems>d__0.MoveNext() at System.ServiceModel.Syndication.Atom10FeedFormatter.WriteItems(XmlWriter writer, IEnumerable`1 items, Uri feedBaseUri) at System.ServiceModel.Syndication.Atom10FeedFormatter.WriteFeedTo(XmlWriter writer, SyndicationFeed feed, Boolean isSourceFeed) at System.ServiceModel.Syndication.Atom10FeedFormatter.WriteFeed(XmlWriter writer) at System.ServiceModel.Syndication.Atom10FeedFormatter.WriteTo(XmlWriter writer) at System.Data.Services.Serializers.SyndicationSerializer.WriteTopLevelElements(IExpandedResult expanded, IEnumerator elements, Boolean hasMoved) at System.Data.Services.Serializers.Serializer.WriteRequest(IEnumerator queryResults, Boolean hasMoved) at System.Data.Services.ResponseBodyWriter.Write(Stream stream) I've kinda narrowed it down to a issue where LinqExtender wraps every returned object, so that my object actually inherits itself - thats at least how it looks like in the debugger. These two queries are basicly the same. The first is the legacy-api where the OrderBy and Select is regular Linq to Objects. The second query is a "real" linq-provider made with LinqExtender. var db = CalendarDataProvider.GetCalendarEntriesByDate(DateTime.Now, DateTime.Now.AddMonths(1), Guid.Empty) .OrderBy(o => o.Title) .Select(o => new ODataCalendarEntry(o)); var query = new ODataCalendarEntryQuery() .Where(o => o.Start > DateTime.Now && o.End < DateTime.Now.AddMonths(1)) .OrderBy(o => o.Title); When returning db for the OData feed everything is fine, but returning query throws a NullRefenceException. I've tried all kind of tricks and even tried to project all the data into a new object like this, but still the same error return query.Select(o => new ODataCalendarEntry { Title = o.Title, Start = o.Start, End = o.End, Name = o.Name });

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  • VS2008 DataSet Wizard doesn't match tables for updating

    - by James H
    Hi all, first question ever on this site. I've been having a real stubborn problem using Visual Studio 2008 and I'm hoping someone has figured this out before. I have 2 libraries and 1 project that use strongly typed datasets (MSSQL backend) that I generated using the "Configure DataSet with Wizard" option on in Data Sources. I've had them working just fine for awhile and I've written a lot of code in the non-designer file for the row classes. I've also specified a lot of custom queries using the dataset designer. This is all work I can't afford to loose. I've recently made some changes to re-organize my libraries which included changing the names of the libraries themselves. I also changed the connection string to point to a different database which is a development copy (same exact schema). Problem is now when I open up "Configure DataSet with Wizard" to pickup a new column I've added to one of the tables it no longer matches the tables correctly in the wizard. The wizard displays all of the tables in the database and none of them have check boxes next to them (ie: are not part of this dataset). Below those it shows all of the tables again but with red Xs and these are checked. Basically meaning that Visual Studio sees all of the tables it currently has in the DataSet and sees all of the tables in the database, but believes they are no longer the same and thus do not match! I've had this same thing happen quite awhile back and I think I just re-built the xsd from scratch and manually copied the code over and then had to redefine all of the custom queries I built in the dataset designer. That's not a good solution. I'm looking for 2 answers: 1. What causes this to happen and how to prevent it. 2. How do I fix this so that the wizard once again believes the tables in its xsd are the same tables that are in the database (yes, they have the exact same names still). Thanks.

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  • IDbTransaction Rollback Timeout

    - by Ben
    I am dealing with an interesting situation where I perform many database updates in a single transaction. If these updates fail for any reason, the transaction is rolled-back. IDbTransaction transaction try { transaction = connection.BeginTransaction(); // do lots of updates (where at least one fails) transaction.Commit(); } catch { transaction.Rollback(); // results in a timeout exception } finally { connection.Dispose(); } I believe the above code is generally considered the standard template for performing database updates within a transaction. The issue I am facing is that whilst transaction.Rollback() is being issued to SQL Server, it is also timing out on the client. Is there anyway of distinguishing between a timeout to issue the rollback command and a timeout on that command executing to completion? Thanks in advance, Ben

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  • Possible to view T-SQL syntax of a stored proc-based SqlCommand?

    - by mconnley
    Hello! I was wondering if anybody knows of a way to retrieve the actual T-SQL that is to be executed by a SqlCommand object (with a CommandType of StoredProcedure) before it executes... My scenario involves optionally saving DB operations to a file or MSMQ before the command is actually executed. My assumption is that if you create a SqlCommand like the following: Using oCommand As New SqlCommand("sp_Foo") oCommand.CommandType = CommandType.StoredProcedure oCommand.Parameters.Add(New SqlParameter("@Param1", "value1")) oCommand.ExecuteNonQuery() End Using It winds up executing some T-SQL like: EXEC sp_Foo @Param1 = 'value1' Is that assumption correct? If so, is it possible to retrieve that actual T-SQL somehow? My goal here is to get the parsing, etc. benefits of using the SqlCommand class since I'm going to be using it anyway. Is this possible? Am I going about this the wrong way? Thanks in advance for any input!

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  • how to update a selectecd record in a dataset an update a onother datatable in another Adoconecion

    - by ml
    I have 2 adoconections and 2 datatables in each conecion (Local Table1_master Table1_Detail) (Network Table1_master Table1_Detail) i show thwm in a DBgrid and now i wouth like to update the (Local Table1_master Table1_Detail) from the tables in (Network Table1_master Table1_Detail) how can i upddate the selected record´s .!!! i try many ways but normaly it insert more recordes and don´t update record i use a .MDB database

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  • How to I serialize a large graph of .NET object into a SQL Server BLOB without creating a large bu

    - by Ian Ringrose
    We have code like: ms = New IO.MemoryStream bin = New System.Runtime.Serialization.Formatters.Binary.BinaryFormatter bin.Serialize(ms, largeGraphOfObjects) dataToSaveToDatabase = ms.ToArray() // put dataToSaveToDatabase in a Sql server BLOB But the memory steam allocates a large buffer from the large memory heap that is giving us problems. So how can we stream the data without needing enough free memory to hold the serialized objects. I am looking for a way to get a Stream from SQL server that can then be passed to bin.Serialize() so avoiding keeping all the data in my processes memory. Likewise for reading the data back... Some more background. This is part of a complex numerical processing system that processes data in near real time looking for equipment problems etc, the serialization is done to allow a restart when there is a problem with data quality from a data feed etc. (We store the data feeds and can rerun them after the operator has edited out bad values.) Therefore we serialize the object a lot more often then we de-serialize them. The objects we are serializing include very large arrays mostly of doubles as well as a lot of small “more normal” objects. We are pushing the memory limit on a 32 bit system and make the garage collector work very hard. (Effects are being made elsewhere in the system to improve this, e.g. reusing large arrays rather then create new arrays.) Often the serialization of the state is the last straw that courses an out of memory exception; our peak memory usage is while this serialization is being done. I think we get large memory pool fragmentation when we de-serialize the object, I expect there are also other problem with large memory pool fragmentation given the size of the arrays. (This has not yet been investigated, as the person that first looked at this is a numerical processing expert, not a memory management expert.) Are customers use a mix of Sql Server 2000, 2005 and 2008 and we would rather not have different code paths for each version of Sql Server if possible. We can have many active models at a time (in different process, across many machines), each model can have many saved states. Hence the saved state is stored in a database blob rather then a file. As the spread of saving the state is important, I would rather not serialize the object to a file, and then put the file in a BLOB one block at a time. Other related questions I have asked How to Stream data from/to SQL Server BLOB fields? Is there a SqlFileStream like class that works with Sql Server 2005?

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  • Conversion failed: SqlParameter and DateTime

    - by Tim
    I'm changing old,vulnerable sqlcommands with SqlParameters but get a SqlException: System.Data.SqlClient.SqlException {"Conversion failed when converting datetime from character string."} on sqlCommand.ExecuteScalar() Dim sqlString As String = _ "SELECT TOP 1 " & _ "fiSL " & _ "FROM " & _ "tabData AS D " & _ "WHERE " & _ "D.SSN_Number = '@SSN_Number' " & _ "AND D.fiProductType = 1 " & _ "AND D.Repair_Completion_Date > '@Repair_Completion_Date' " & _ "ORDER BY " & _ "D.Repair_Completion_Date ASC" Dim obj As Object Dim sqlCommand As SqlCommand Try sqlCommand = New SqlCommand(sqlString, Common.MyDB.SqlConn_RM2) sqlCommand.CommandTimeout = 120 sqlCommand.Parameters.AddWithValue("@SSN_Number", myClaim.SSNNumber) sqlCommand.Parameters.AddWithValue("@Repair_Completion_Date", myClaim.RepairCompletionDate) If Common.MyDB.SqlConn_RM2.State <> System.Data.ConnectionState.Open Then Common.MyDB.SqlConn_RM2.Open() obj = sqlCommand.ExecuteScalar() Catch ex As Exception Dim debug As String = ex.ToString Finally Common.MyDB.SqlConn_RM2.Close() End Try myClaim.RepairCompletionDate is a SQLDateTime. Do i have to remove the quotes in the sqlString to compare Date columns? But then i dont get a exception but incorrect results.

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  • how to update a selected record in a dataset and update another datatable in another Adoconnection?

    - by ml
    I have 2 adoconnections and 2 datatables in each connection (Local Table1_master Table1_Detail) (Network Table1_master Table1_Detail). I show them in a DBgrid and now I would like to update the (Local Table1_master Table1_Detail) from the tables in (Network Table1_master Table1_Detail). How can I update the selected records? I have tried many ways but normally it inserts more records and doesn´t update the record. I use a .MDB database.

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  • Why would it be a bad idea to have database connection open between client requests?

    - by AspOnMyNet
    1) Book I’m reading argues that connections shouldn’t be opened between client requests, since they are a finite resource. I realize that max pool size can quickly be reached and thus any further attempts to open a connection will be queued until connection becomes available and for that reason it would be imperative that we release connection as soon as possible. But assuming all request will open connection to the same DB, then I’m not sure how having a connection open between two client requests would be any less efficient than having each request first acquiring a connection from connection pool and later returning that object to connection pool? 2) Book also recommends that when database code is encapsulated in a dedicated data access class, then method M opening a database connection should also close that connection. a) I assume one reason why M should also close it, is because if method M opening the connection doesn’t also close it, but instead this connection object is used inside several methods, then it’s more likely that a programmer will forget to close it. b) Are there any other reasons why a method opening the connection should also close it? thanx

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  • Exception opening TAdoDataset: Arguments are of the wrong type, are out of acceptable range, or are

    - by Dave Falkner
    I've been trying to debug the following problem for several weeks now - this method is called from several places within the same datamodule, but this exception (from the subject line of this post) only occurs when integers for a certain purpose (pickup orders vs. orders that we ship through a carrier) are used - and don't ask me how the application can tell the difference between one integer's purpose and another! Furthermore, I cannot duplicate this issue on my machine - the error occurs on a warehouse machine but not my own development machine, even when working with the same production database. I have suspected an MDAC version conflict between the two machines, but have run a version checker and confirmed that both machines are running 2.8, and additionally have confirmed this by logging the TAdoDataset's .Version property at runtime. function TdmESShip.SecondaryID(const PrimaryID : Integer ): String; begin try with qESPackage2 do begin if Active then Close; LogMessage('-----------------------------------'); LogMessage('Version: ' + FConnection.Version); LogMessage('DB Info: ' + FConnection.Properties['Initial Catalog'].Value + ' ' + FConnection.Properties['Data Source'].Value); LogMessage('Setting the parameter.'); Parameters.ParamByName('ParameterName').Value := PrimaryID; LogMessage('Done setting the parameter.'); Open; Ninety-nine times out of 100 this logging code logs a successful operation as follows: Version: 2.8 DB Info: (database name and instance) Setting the parameter. Done setting the parameter. Opened the dataset. But then whenever a "pickup" order is processed, this exception gets thrown whenever the dataset is opened: Version: 2.8 DB Info: (database name and instance) Setting the parameter. Done setting the parameter. GetESPackageID() threw an exception. Type: EOleException, Message: Arguments are of the wrong type, are out of acceptable range, or are in conflict with one another Error: Arguments are of the wrong type, are out of acceptable range, or are in conflict with one another for packageID 10813711 I've tried eliminating the parameter and have built the commandtext for this dataset programmatically, suspecting that some part of the TParameter's configuration might be out of whack, but the same error occurs under the same circumstances. I've tried every combination of TParameter properties that I can think of - this is the millionth TParameter I've created for my millionth dataset, and I've never encountered this error. I've even created a second dataset from scratch and removed all references to the original dataset in case some property of the original dataset in the .dfm might be corrupted, but the same error occurs under the same circumstances. The commandtext for this dataset is a simple select ValueA from TableName where ValueB = @ParameterB I'm about ready to do something extreme, such as writing a web service to look these values up - it feels right now as though I could destroy my machine, rebuild it, rewrite this entire application from scratch, and the application would still know to throw an exception whenever I try to look up a secondary value from a primary value, but only for pickup orders, and only from the one machine in the warehouse, but I'm probably missing something simple. So, any help anyone could provide would be greatly appreciated.

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  • How to connect an existing strongly-typed data set to a different server at run time?

    - by Kiril
    I am coding a simple space empire management game in Visual C# 2008, which relies on connecting to a remote SQL server database to get/store data. I would like the user to be able to connect to a user-specified SQL server from the login screen(he specifies IP address, port, database name, ID, password and presses "connect" button). However, I found out that the Dataset connection string property is read only and cannot be changed. Is there any way to guide the wizard-generated DataSet to a user-specified server at run time?

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  • SQLiteDataAdapter Update method returning 0

    - by Lirik
    I loaded 83 rows from my CSV file, but when I try to update the SQLite database I get 0 rows... I can't figure out what I'm doing wrong. The program outputs: Num rows loaded is 83 Num rows updated is 0 The source code is: public void InsertData(String csvFileName, String tableName) { String dir = Path.GetDirectoryName(csvFileName); String name = Path.GetFileName(csvFileName); using (OleDbConnection conn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + dir + @";Extended Properties=""Text;HDR=Yes;FMT=Delimited""")) { conn.Open(); using (OleDbDataAdapter adapter = new OleDbDataAdapter("SELECT * FROM " + name, conn)) { QuoteDataSet ds = new QuoteDataSet(); adapter.Fill(ds, tableName); Console.WriteLine("Num rows loaded is " + ds.Tags.Rows.Count); InsertData(ds, tableName); } } } public void InsertData(QuoteDataSet data, String tableName) { using (SQLiteConnection conn = new SQLiteConnection(_connectionString)) { using (SQLiteDataAdapter sqliteAdapter = new SQLiteDataAdapter("SELECT * FROM " + tableName, conn)) { using (new SQLiteCommandBuilder(sqliteAdapter)) { conn.Open(); Console.WriteLine("Num rows updated is " + sqliteAdapter.Update(data, tableName)); } } } } Any hints on why it's not updating the correct number of rows?

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  • Procedure or function expects parameter which was not supplied

    - by eftpotrm
    Driving me mad on a personal project; I know I've done this before but elsewhere and don't have the code. As far as I can see, I'm setting the parameter, I'm setting its value, the connection is open, yet when I try to fill the dataset I get the error 'Procedure or function expects parameter "@test" which was not supplied'. (This is obviously a simplified test! Same error on this or the real, rather longer code though.) C#: SqlCommand l_oCmd; DataSet l_oPage = new DataSet(); l_oCmd = new SqlCommand("usp_test", g_oConn); l_oCmd.Parameters.Add(new SqlParameter("@test", SqlDbType.NVarChar)); l_oCmd.Parameters[0].Value = "hello world"; SqlDataAdapter da = new SqlDataAdapter(l_oCmd); da.Fill(l_oPage); SQL: create procedure usp_test ( @test nvarchar(1000) ) as select @test What have I missed?

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  • Can I get a reference to a pending transaction from a SqlConnection object?

    - by Rune
    Hey, Suppose someone (other than me) writes the following code and compiles it into an assembly: using (SqlConnection conn = new SqlConnection(connString)) { conn.Open(); using (var transaction = conn.BeginTransaction()) { /* Update something in the database */ /* Then call any registered OnUpdate handlers */ InvokeOnUpdate(conn); transaction.Commit(); } } The call to InvokeOnUpdate(IDbConnection conn) calls out to an event handler that I can implement and register. Thus, in this handler I will have a reference to the IDbConnection object, but I won't have a reference to the pending transaction. Is there any way in which I can get a hold of the transaction? In my OnUpdate handler I want to execute something similar to the following: private void MyOnUpdateHandler(IDbConnection conn) { var cmd = conn.CreateCommand(); cmd.CommandText = someSQLString; cmd.CommandType = CommandType.Text; cmd.ExecuteNonQuery(); } However, the call to cmd.ExecuteNonQuery() throws an InvalidOperationException complaining that "ExecuteNonQuery requires the command to have a transaction when the connection assigned to the command is in a pending local transaction. The Transaction property of the command has not been initialized". Can I in any way enlist my SqlCommand cmd with the pending transaction? Can I retrieve a reference to the pending transaction from the IDbConnection object (I'd be happy to use reflection if necessary)?

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  • Cyclic References and WCF

    - by Kunal
    I have generated my POCO entities using POCO Generator, I have more than 150+ tables in my database. I am sharing POCO entities all across the application layers including the client. I have disabled both LazyLoading and ProxyCreation in my context.I am using WCF on top of my data access and business layer. Now, When I return a poco entity to my client, I get an error saying "Underlying connection was closed" I enabled WCF tracing and found the exact error : Contains cycles and cannot be serialized if reference tracking is disabled. I Looked at MSDN and found solutions like setting IsReference=true in the DataContract method atttribute but I am not decorating my POCO classes with DataContracts and I assume there is no need of it as well. I won't be calling that as a POCO if I decorate a class with DataContract attribute Then, I found solutions like applying custom attribute [CyclicReferenceAware] over my ServiceContracts.That did work but I wanted to throw this question to community to see how other people managed this and also why Microsoft didn't give built in support for figuring out cyclic references while serializing POCO classes

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  • Auditing in Entity Framework.

    - by Gabriel Susai
    After going through Entity Framework I have a couple of questions on implementing auditing in Entity Framework. I want to store each column values that is created or updated to a different audit table. Rightnow I am calling SaveChanges(false) to save the records in the DB(still the changes in context is not reset). Then get the added | modified records and loop through the GetObjectStateEntries. But don't know how to get the values of the columns where their values are filled by stored proc. ie, createdate, modifieddate etc. Below is the sample code I am working on it. //Get the changed entires( ie, records) IEnumerable<ObjectStateEntry> changes = context.ObjectStateManager.GetObjectStateEntries(EntityState.Modified); //Iterate each ObjectStateEntry( for each record in the update/modified collection) foreach (ObjectStateEntry entry in changes) { //Iterate the columns in each record and get thier old and new value respectively foreach (var columnName in entry.GetModifiedProperties()) { string oldValue = entry.OriginalValues[columnName].ToString(); string newValue = entry.CurrentValues[columnName].ToString(); //Do Some Auditing by sending entityname, columnname, oldvalue, newvalue } } changes = context.ObjectStateManager.GetObjectStateEntries(EntityState.Added); foreach (ObjectStateEntry entry in changes) { if (entry.IsRelationship) continue; var columnNames = (from p in entry.EntitySet.ElementType.Members select p.Name).ToList(); foreach (var columnName in columnNames) { string newValue = entry.CurrentValues[columnName].ToString(); //Do Some Auditing by sending entityname, columnname, value } }

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  • SqlParameter contructor compiler overload choice

    - by Ash
    When creating a SqlParameter (.NET3.5) or OdbcParameter I often use the SqlParameter(string parameterName, Object value) constructor overload to set the value in one statement. When I tried passing a literal 0 as the value paramter I was initially caught by the C# compiler choosing the (string, OdbcType) overload instead of (string, Object). MSDN actually warns about this gotcha in the remarks section, but the explanation confuses me. Why does the C# compiler decide that a literal 0 parameter should be converted to OdbcType rather than Object? The warning also says to use Convert.ToInt32(0) to force the Object overload to be used. It confusingly says that this converts the 0 to an "Object type". But isn't 0 already an "Object type"? The Types of Literal Values section of this page seems to say literals are always typed and so inherit from System.Object. This behavior doesn't seem very intuitive given my current understanding? Is this something to do with Contra-variance or Co-variance maybe?

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