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  • Can I use a single DateTime field on the Entity Framework model side when the value is stored in a set of Int fields in the actual database?

    - by Ivan
    The actual table in the database has separate integer fields for storing year, month, day, hour and minute values (all in UTC) (seconds and milliseconds are irrelevant for my task and considered equal to zero). Needless to say it would be of great convenience to have just one field of DateTime type on the application side and hide all the conversion under the cover of the Entity Framework model code. Any directions on how to do that? I am not very experienced with Entity Framework yet.

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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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  • How to select top n rows from a datatable/dataview in asp.net

    - by skamale
    How to select top n rows from a datatable/dataview in asp.net.currently I am using the following code by passing the table and number of rows to get the records but is there a better way. public DataTable SelectTopDataRow(DataTable dt, int count) { DataTable dtn = dt.Clone(); for (int i = 0; i < count; i++) { dtn.ImportRow(dt.Rows[i]); } return dtn; }

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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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  • Can a stateless WCF service benefit from built-in database connection pooling?

    - by vladimir
    I understand that a typical .NET application that accesses a(n SQL Server) database doesn't have to do anything in particular in order to benefit from the connection pooling. Even if an application repeatedly opens and closes database connections, they do get pooled by the framework (assuming that things such as credentials do not change from call to call). My usage scenario seems to be a bit different. When my service gets instantiated, it opens a database connection once, does some work, closes the connection and returns the result. Then it gets torn down by the WCF, and the next incoming call creates a new instance of the service. In other words, my service gets instantiated per client call, as in [ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall)]. The service accesses an SQL Server 2008 database. I'm using .NET framework 3.5 SP1. Does the connection pooling still work in this scenario, or I need to roll my own connection pool in form of a singleton or by some other means (IInstanceContextProvider?). I would rather avoid reinventing the wheel, if possible.

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  • DataView Vs DataTable.Select()

    - by Aseem Gautam
    Considering the code below: Dataview someView = new DataView(sometable) someView.RowFilter = someFilter; if(someView.count > 0) { …. } Quite a number of articles which say Datatable.Select() is better than using DataViews, but these are prior to VS2008. Solved: The Mystery of DataView's Poor Performance with Large Recordsets Array of DataRecord vs. DataView: A Dramatic Difference in Performance So in a situation where I just want a subset of datarows based on some filter criteria(single query) and what is better DataView or DataTable.Select()?

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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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  • ASP.Net Layered app - Share Entity Data Model amongst layers

    - by Chris Klepeis
    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.

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  • Association not imported in EF4 designer for non-primary key

    - by Rommel Manalo
    The relationship 'FK_EXTERNAL_ISMARKETI_MARKETIN' has columns that are not part of the key of the table on the primary side of the relationship. The relationship was excluded. USE [Instruments.UnitTest] GO ALTER TABLE [Instr].[ExternalIdentification] WITH CHECK ADD CONSTRAINT [FK_EXTERNAL_ISMARKETI_MARKETIN] FOREIGN KEY([InstrumentID], [MarketInstrumentID]) REFERENCES [Instr].[MarketInstrument] ([InstrumentID], [MarketInstrumentID]) GO ALTER TABLE [Instr].[ExternalIdentification] CHECK CONSTRAINT [FK_EXTERNAL_ISMARKETI_MARKETIN] GO I'm using an association for NON-PRIMARY KEY columns, is this possible in the EF4?

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  • Importing an Excel WorkSheet into a Datatable

    - by Nick LaMarca
    I have been asked to create import functionality in my application. I am getting an excel worksheet as input. The worksheet has column headers followed by data. The users want to simply select an xls file from their system, click upload and the tool deletes the table in the database and adds this new data. I thought the best way would be too bring the data into a datatable object and do a foeach for every row in the datatable insert row by row into the db. My question is what can anyone give me code to open an excel file, know what line the data starts on in the file, and import the data into a datable object?

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  • Why is sql server giving a conversion error when submitting date.today to a datetime column?

    - by kpierce8
    I am getting a conversion error every time I try to submit a date value to sql server. The column in sql server is a datetime and in vb I'm using Date.today to pass to my parameterized query. I keep getting a sql exception Conversion failed when converting datetime from character string. Here's the code Public Sub ResetOrder(ByVal connectionString As String) Dim strSQL As String Dim cn As New SqlConnection(connectionString) cn.Open() strSQL = "DELETE Tasks WHERE ProjID = @ProjectID" Dim cmd As New SqlCommand(strSQL, cn) cmd.Parameters.AddWithValue("ProjectID", 5) cmd.ExecuteNonQuery() strSQL = "INSERT INTO Tasks (ProjID, DueDate, TaskName) VALUES " & _ " (@ProjID, @TaskName, @DueDate)" Dim cmd2 As New SqlCommand(strSQL, cn) cmd2.CommandText = strSQL cmd2.Parameters.AddWithValue("ProjID", 5) cmd2.Parameters.AddWithValue("DueDate", Date.Today) cmd2.Parameters.AddWithValue("TaskName", "bob") cmd2.ExecuteNonQuery() cn.Close() DataGridView1.DataSource = ds.Projects DataGridView2.DataSource = ds.Tasks End Sub Any thoughts would be greatly appreciated.

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  • datalist itemdatabound event having issues changing item bg color on condition

    - by Jreeter
    Hey guys I'm trying to do something really simple.. I'm checking a data column in my datarow if it's 0 I want the item back color in the datalist to be green if its < 0 remain transparent... if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem) { DataRowView drv = (DataRowView)(e.Item.DataItem); int rating = int.Parse(drv.Row["rating"].ToString()); if (rating > 0) { e.Item.BackColor = System.Drawing.Color.Green; } } I've stepped through with debugger and it's hitting all the conditions the color just isn't changing.. I know it has to be something simple I just can't see it.

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  • .NET - Is there a way to programmatically fill all tables in a strongly-typed dataset?

    - by Mike Loux
    Hello, all! I have a SQL Server database for which I have created a strongly-typed DataSet (using the DataSet Designer in Visual Studio 2008), so all the adapters and select commands and whatnot were created for me by the wizard. It's a small database with largely static data, so I would like to pull the contents of this DB in its entirety into my application at startup, and then grab individual pieces of data as needed using LINQ. Rather than hard-code each adapter Fill call, I would like to see if there is a way to automate this (possibly via Reflection). So, instead of: Dim _ds As New dsTest dsTestTableAdapters.Table1TableAdapter.Fill(_ds.Table1) dsTestTableAdapters.Table2TableAdapter.Fill(_ds.Table2) <etc etc etc> I would prefer to do something like: Dim _ds As New dsTest For Each tableName As String In _ds.Tables Dim adapter as Object = <routine to grab adapter associated with the table> adapter.Fill(tableName) Next Is that even remotely doable? I have done a fair amount of searching, and I wouldn't think this would be an uncommon request, but I must be either asking the wrong question, or I'm just weird to want to do this. I will admit that I usually prefer to use unbound controls and not go with strongly-typed datasets (I prefer to write SQL directly), but my company wants to go this route, so I'm researching it. I think the idea is that as tables are added, we can just refresh the DataSet using the Designer in Visual Studio and not have to make too many underlying DB code changes. Any help at all would be most appreciated. Thanks in advance!

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  • why DataColumn AllowDbNull is true even if oracle db does not allow null

    - by matti
    Hi. I have column SomeId in table SomeLink. When I look with tOra or Sql Plus Worksheet both state: tOra: Column name Data type Default Null Comment SOMEID INTEGER {null} NOT NULL {null} Sql Plus: SOMEID NOT NULL NUMBER(38) I have authored a method that's intended to give default values to all NOT NULL fields that don't have values: public static void GetDefaultValuesForNonNullColumns(DataRow row) { foreach(DataColumn col in row.Table.Columns) { if (Convert.IsDBNull(row[col]) && !col.AllowDBNull) { if (ColumnIsNumeric(col.DataType)) row[col] = 0; else if (col.DataType == typeof(DateTime)) row[col] = DateTime.Now; else if (col.DataType == typeof(String)) row[col] = string.Empty; else if (col.DataType == typeof(Char)) row[col] = ' '; else throw new Exception(string.Format("Unsupported column type: {0}", col.DataType)); } } } When SOMEID is handled in loop the AllowDBNull = true. I really can't understand. The table is created in DataSet like this: _someLinkAdptr = _dbFactory.CreateDataAdapter(); _someLinkAdptr.SelectCommand = _dbFactory.CreateCommand(); _someLinkAdptr.SelectCommand.Connection = _cnctn; _someLinkAdptr.SelectCommand.CommandText = GetSomeLinkSelectTxtAndParams(_someLinkAdptr.SelectCommand, UndefinedValue.ToString(), UndefinedValue.ToString()); Select command returns no rows. The idea is that I can then use commandbuilder to get InsertCommand without building it myself. The row is added to dataset's table like this: private static void CreateDocLink(int anId, int anotherId) { DataRow row = _someDataSet.Tables["SomeLink"].NewRow(); row["AnId"] = anId; row["AnotherId"] = anotherId; Utility.GetDefaultValuesForNonNullColumns(row); _someDataSet.Tables["SomeLink"].Rows.Add(row); } When DataAdapter is updated to oracle db I get: ORA-01400: cannot insert NULL into (SOMESCHEMA.SOMELINK.SOMEID) Cheers & BR -Matti

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  • C# SQL Data Adapter System.Data.StrongTypingException

    - by René
    I get my data from SQL to Dataset with Fill. It's just one table with two columns (CategoryId (int) and CategoryName (varchar)). When I look at my dataset after fill method, CategoryId Columns seems to be correct. But in the CategoryName I have a *System.Data.StrongTypingExceptio*n. What could that mean? Any Ideas?

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  • Can Entity Framework be used for the purpose of entity/schema definition at application runtime?

    - by Kabeer
    Hello. Can 'Entity Framework' be used for the purpose of entity definition at application runtime? Ok, to make it simple, here is what I want to achieve: My application is a product. I should be able to define entities at runtime on the basis of inputs gathered from an 'authoring' user (in effect this means 'model first' approach). These entities are of course persistable. Further, after having defined the entities and their relationships, I should be able to make complex queries across them for many reasons, including reports. Is the above possible and how? So far what I have realized is that there is a dependency on Visual Studio.

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  • ObjectDataSource Insert and Update methods error

    - by Jack
    I m developing asp.net 3.5 project. When I want to Insert with DetailsView this error occured: Error : ObjectDataSource 'ObjectDataSource2' could not find a non-generic method 'AddCity' that has parameters: CITY_NAME. <asp:ObjectDataSource ID="ObjectDataSource2" runat="server" SelectMethod="GetCityByID" UpdateMethod="UpdateCity" InsertMethod="AddCity" TypeName="NOP_CRM.Lib.nop_cities" OldValuesParameterFormatString="original_{0}"> <SelectParameters> <asp:ControlParameter ControlID="GridView1" Name="cityid" PropertyName="SelectedValue" Type="Int32" DefaultValue="1" /> </SelectParameters> <UpdateParameters> <asp:Parameter Name="CITY_NAME" Type="String" /> </UpdateParameters> <InsertParameters> <asp:Parameter Name="CITY_NAME" Type="String" /> </InsertParameters> </asp:ObjectDataSource> ... public int AddCity(string cityname) { CITY_NAME = cityname; Insert(); return _CITY_ID; }

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  • linq, selecting columns as IEnumerable<DataRow>

    - by joe
    how can i do in linq: IEnumerable<DataRow> query = from rec in dt.AsEnumerable() where rec.Field<decimal>("column2") == 1 && foo(rec.Field<decimal>("column1")) select new { column1 = rec.Field<decimal>("column1"), column2 = rec.Field<decimal>("column2"), column3 = rec.Field<decimal>("column3")} ; this does not work. Im trying to select some columns as new datatable then join it later with some other datatable.

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  • ASP.NET SqlDataReader throwing error: Invalid attempt to call Read when reader is closed.

    - by Bugget
    This one has me stumped. Here are the relative bits of code: public AgencyDetails(Guid AgencyId) { try { evgStoredProcedure Procedure = new evgStoredProcedure(); Hashtable commandParameters = new Hashtable(); commandParameters.Add("@AgencyId", AgencyId); SqlDataReader AppReader = Procedure.ExecuteReaderProcedure("evg_getAgencyDetails", commandParameters); commandParameters.Clear(); //The following line is where the error is thrown. Errormessage: Invalid attempt to call Read when reader is closed. while (AppReader.Read()) { AgencyName = AppReader.GetOrdinal("AgencyName").ToString(); AgencyAddress = AppReader.GetOrdinal("AgencyAddress").ToString(); AgencyCity = AppReader.GetOrdinal("AgencyCity").ToString(); AgencyState = AppReader.GetOrdinal("AgencyState").ToString(); AgencyZip = AppReader.GetOrdinal("AgencyZip").ToString(); AgencyPhone = AppReader.GetOrdinal("AgencyPhone").ToString(); AgencyFax = AppReader.GetOrdinal("AgencyFax").ToString(); } AppReader.Close(); AppReader.Dispose(); } catch (Exception ex) { throw new Exception("AgencyDetails Constructor: " + ex.Message.ToString()); } } And the implementation of ExecuteReaderProcedure: public SqlDataReader ExecuteReaderProcedure(string ProcedureName, Hashtable Parameters) { SqlDataReader returnReader; using (SqlConnection conn = new SqlConnection(connectionString)) { try { SqlCommand cmd = new SqlCommand(ProcedureName, conn); SqlParameter param = new SqlParameter(); cmd.CommandType = System.Data.CommandType.StoredProcedure; foreach (DictionaryEntry keyValue in Parameters) { cmd.Parameters.AddWithValue(keyValue.Key.ToString(), keyValue.Value); } conn.Open(); returnReader = cmd.ExecuteReader(CommandBehavior.CloseConnection); } catch (SqlException e) { throw new Exception(e.Message.ToString()); } } return returnReader; } The connection string is working as other stored procedures in the same class run fine. The only problem seems to be when returning SqlDataReaders from this method! They throw the error message in the title. Any ideas are greatly appreciated! Thanks in advance!

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  • visusal studio embedded crystal report keeps prompting database login?

    - by phill
    I'm using visual studio 2005 to develop a form with a combobox passing a value into the parameter of an embedded crystal report. I'm trying to figure out why it keeps prompting me for a database login every single time you try to run the report with a different combobox selection. Here is my code: private Sub Form1_load... Dim ConnName As String Dim ServerName As String Dim DBName As String Dim user As String Dim pass As String Dim gDBA As ADODB.Connection Dim records As ADODB.Recordset Dim datver As ADODB.Recordset Dim query As String '---OPEN THE DATABASE CONNECTIONS gDBA = New ADODB.Connection ': gDBA.CursorLocation = adUseServer 'Added to prevent time out error gDBA.CommandTimeout = 1000 : gDBA.ConnectionTimeout = 1000 gDBA.ConnectionString = "Server=svr13;Database=subscribers;User ID=KViews;Password=Solution;Trusted_Connection=True;" gDBA.Open("Data Source=Kaseya;Initial Catalog=subscribers;User Id=KViews;Password=Solution;", "KViews", "Solution") records = New ADODB.Recordset query = "select distinct groupname from _v_k order by groupname desc" 'records.ActiveConnection = gDBA.ConnectionString records.CursorType = CursorTypeEnum.adOpenForwardOnly records.LockType = LockTypeEnum.adLockReadOnly records.Open(query, gDBA) Do While Not records.EOF ComboBox1.Items.Add(records.Fields("groupname").Value) records.MoveNext() Loop end Sub Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim selected As String selected = ComboBox1.Text Dim cryRpt As New ReportDocument cryRpt.Load("C:\Visual Studio 2005\Projects\WindowsApplication1\WindowsApplication1\CrystalReport1.rpt") cryRpt.SetDatabaseLogon("KViews", "Solutions", "svr13", "subscribers") cryRpt.SetParameterValue("companyname", selected) CrystalReportViewer1.ReportSource = cryRpt CrystalReportViewer1.Refresh() End Sub I looked at this previous posting http://stackoverflow.com/questions/1132314/database-login-prompt-with-crystal-reports but this wasn't very helpful. I couldn't find where a CMC was to disable the prompt. Any ideas? thanks in advance

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