Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data

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  - 1
    - Add column using Dataset Designer => hosed project Context: VS2008 SQL Server Compact 3.5 database Problem: I used the Dataset Designer to add a column to a table (right click on table in designer, Add->Column). How do I update the database to correspond with this change? I tried locating the database in my Server Explorer and adding the identical column by hand using the Table Properties. Run the project and try to stuff some data in the newly modifed table...all original columns get data but the new column only gets NULLs. Try to use "Configure DataSet with Wizard" from Data Sources tab...get warning that "The selected dataset contains objects that can only be viewed with the Dataset Designer." Which I don't understand because I made what seems a trivial modification to a table. It seems there is no correspondence between the new column in the database and the new column in the dataset. If I access the new column's DataColumn properties in DataSet Designer, the entry for the "Source" property is empty, and the dropdown selector only sees the original columns in the table, not the new one. Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144880
  - 2
    - Databinding to a TextBox in WPF Is it possible to bind an IList<string> to a TextBox and show the first value and use Buttons to navigate forward and backwards through the data? I have a window with just 3 controls: 1. Previous Button 2. TextBox 3. Next button My goal is to bind a collection of names to the TextBox and be able to cyle through them with the two navigation buttons. Here's the code behind I have in place for a XAML (WPF) window: ------------------------------------ private ListCollectionView view; public DataNavigator() { InitializeComponent(); ICollection<string> names = new Data().GetJustNames(); DataContext = names; view = (ListCollectionView) CollectionViewSource.GetDefaultView(DataContext); view.CurrentChanged += view_CurrentChanged; } void view_CurrentChanged(object sender, System.EventArgs e) { btnPrevious.IsEnabled = (view.CurrentPosition > 0); btnNext.IsEnabled = (view.CurrentPosition < view.Count-1); } private void btnNext_Click(object sender, RoutedEventArgs e) { view.MoveCurrentToNext(); } private void btnPrevious_Click(object sender, RoutedEventArgs e) { view.MoveCurrentToPrevious(); } --------------------------------------------------------------------------------------------- Now I'm pretty sure the navigation is working because the buttons become disabled correctly. My only question is how do I set the binding to the TextBox.Text property in XAML? <TextBox Margin="139,56.5,169,65.5" Name="tbName" Text="{Binding Path=?}"/> I'm not sure what the Path should be. I don't think I have to set the source because the TextBox is within the DataContext right? Thanks for any insight you might be able to provide! Mark Moeykens Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144878
  - 3
    - Varbinary column in a DataTable Using SQL Server 2005, Visual Studio 2005 (8.0.50727.762) Framework 2.0.50727 SP1 I have a varbinary column in my database. I am trying to set the DataColumn.DataType in the dataset designer to byte[] but it is not in the selection list. I tried changing it in the xxxxx.Designer.cs file but of course the changes were lost when the project was re-built. What is the solution? Can I code this.columnMissionStatusImage = new global::System.Data.DataColumn("MissionStatusImage", typeof(byte[]), null, global::System.Data.MappingType.Element); in the .cs file? If so, what event do I put it in? Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144876
  - 4
    - LINQ derived NullReference NullReferenceException when Inserting from derived class STEPS to reproduce: 1- Define a database table Foo(ID:int(PK), Name:nchar(10)) 2- Create an application project. 3- Define a LINQ to SQL model and add entity 'Foo' from the created table. 4- Add a new class 'FooEx' to the project, inherit it from 'Foo', 5. Add an extra property of type 'int' named 'ExtraInfo' to FooEx. 6. Add a statically initialized DataContext to FooEx 7. Create a public method Insert in FooEx 8. In the insert method put db.Foos.InsertOnSubmit(this); where db is the DataContext instance for the class 9. In the insert method put db.SubmitChanges; where db is the DataContext instance for the class 10. Enter and execute the following code in 'Main' or button click or such. FooEx f = new FooEx(); f.ID = 1; f.Name = "OhOh"; f.Insert(); Actual ResultsUpon executing the described project, the following exception is thrown when trying to attach the record: NullReferenceException: Message: "Object reference not set to an instance of an object." Occurs on â?? InsertOnSubmit. update fails similarly Note: linq should have its own newsgroup- currently it is being entered in C#, Framework, and this one Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144870
  - 5
    - How to Update an existing schema on a typed dataset I need to do what seemes a simple task, but i am stuck. I have a column in my database i need to change from 7 chars to 10 chars. I have a number of strongly typed datasets in my system that use this table. I attempted to edit the xsd file in the designer and changed the 7 to a 10. But the underlaying class file did not get updated. When i searched for the column i need to change it still was set to 7. Then I attempted to run the "Table Adapter Configuration Widard". This actually broke the application and it would not compile. I then noticed that duplicate colmns appeared in the table in the dataset. For example there was ProjectId and ProjectId1. ProjectId1 did not exist before. I hope i am missing something simple here. I did change the code generated files to widen the columns in question and the app seemed to work ok, but i am sure this is not the prefered way to go, any help would be appreciated. Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144868
  - 6
    - Replacement for dataadapter Hi Experts, I am having new problem again. This is regarding SqlDataAdapter fill method performance. Even though its discussed several times my problem is little different. I had migrated one VB6 application to .Net 2.0. In VB6 application they were using RecordSet. Like, ---------------------- Dim rs As New ADODB.Recordset cnn.Open GetDataProvider() rs.Open cSQLUpdateTimeSeries, cnn, adOpenDynamic, adLockPessimistic ---------------------- Later, RecordSet get updated, Like ---------------------- For k = LBound(data, 1) To UBound(data, 1) rs.AddNew rs![sessionID] = session . . . rs![ReportingDate] = Dates(LBound(Dates, 1), k) . . Next rs.Update End If Next rs.Close cnn.Close ---------------------- When I migrated the code to ASP.Net 2.0, I used SqlDataAdapter. ---------------------- adap = New SqlDataAdapter(cSQLUpdateRequest, cnn) Dim cmdBuilder As SqlCommandBuilder = New SqlCommandBuilder(adap) adap.InsertCommand = cmdBuilder.GetInsertCommand() adap.Fill(dt) ---------------------- Here in between some calculation is happening and need to update in database. Dataset is updated like, ---------------------- For k = LBound(data, 1) To UBound(data, 1) Dim dr As DataRow = dt.NewRow() dr("sessionID") = session . . . dr("ReportingDate") = Dates(LBound(Dates, 1), k) . . dt.Rows.Add(dr) Next adap.Update(dt) ---------------------- Here my problem is <b> adap.Fill(dt) </b> is extemly slow and Is there any different approach for the above scenario to update the database (otherthan using adapter) ? Thank you Sriharsha Karagodu Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144867
  - 7
    - Databinding to a listview Hi, I'm trying to populate a list box using a dataset. The data set is tested fine to have data in it but when I run the app, the listbox does not get populated. Below is what I'm doing: Class1 myclass = new Class1(); myclass.Server = "LAPTOP"; myclass.DB = "Northwind"; DataSet ds = myclass.ReturnDS(); ListBox1.DataSource = ds.Tables[0]; ListBox1.DataTextField = "CustomerID"; ListBox1.DataBind(); // works ok, returns field so Dataset contains data Page.Response.Write(ds.Tables[0].Rows[0][0].ToString(); Why doesn't this work? Many thanks for any ideas in advance Ant Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144866
  - 8
    - DataContext - how to use Hi, I'm using LINQ for the first time in a "full" projekt and need some help on how to manage the datacontext. When having one function calling other functions doing LINQ work (select and or update) should I pass the datacontext along as a parameter (ei create one and use that), og should I let functions create (and dispose) there own datacontext? Do you have any advise about using a static global datacontext? Thanks Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144863
  - 9
    - Q: dynamically created databound controls persist but static controls I am running into a case where I am databinding a control (dropdown, checkboxlist, etc) to a datatable, caching the datatable in session, and on postback rebind the control. After postback the control loses its value. However if I try this with a dynamically created control, it maintains state just fine. (I would think it would be the other way around.) You can cut/paste my aspx and codebehind into your project from here: http://www.geocities.com/usenet_daughter/databind_persist_issue.htm How would you get the static control (CheckBoxList1) to maintain state after postback? I am curious why this is happening. Thanks Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144860
  - 10
    - Where to: Questions About EDM and CSDL We are about to start serious design on a new app here. I would like to use the Entity Framework stuff that's new in Framework 3.5 and since it's not even officially released yet, I'm sure to have some questions. So my question is "microsoft.public.dotnet.framework.adonet" the best group to ask questions about EDM and CSDL or is there a more appropriate place to do so? Writing the schemas by hand doesn't look all that appealing but it's still light-years better than writing a million SQL stored procedures. Our userbase is relatively small but they want the app ASAP, so I'm less worried about any potential loss of performance by eliminating SQL stored procedures and more motivated by reduced development time and lower maintenance requirements. Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144857
  - 11
    - How to read sequentially from a random point in a large Xml File. Hello Have a huge XML file with multitudes of "LogEntry" nodes / text lines. A small sample of this xml/text content is below. The file could be anywhere between 200 to 2000 MB. My questions comes in two parts. (A) I would like a solution (or ideas for it), in C#, -- to randomly access a really huge xml file, and to sequentially read only the "memory permiting" number of nodes into memory, from a place randomly selected in the huge file. The application otherwise returns an out of memory error or gets very slow, if i try to load the entire file, because the user like to "scroll" through the file, viewing different parts. Like when scrolling through a huge Word document. How is this (best) done? (B) What is, and/or how would i estimate, the max amount of xml or text from the file that the application can have in it's memory? The application is both a web applicatin and a windows standalone. On a 32bit machine with 2GB Ram, the virual memory is 2GB, which gives an answer. But i have a Java app that goes in a unhandled heap error already when loading xml from a 200MB size file. Any ideas, solutions, or links concerning the above (especially (A))? One avenue is to try to base a sequential reader on a random access stream. I tried this idea. I based the XmlTextReader (for seqeuntial read) on the FileStream (for randon access), but this didnt work. There is some test code at the bottom of this email that shows some of this. I used the FileStream for random access via the FileStream.Seek(..) method. But the XmlTextReader.Read() didn't start reading from the new position. The following: FileStream.Seek(<Random NewPosition>, SeekOrigin.Begin); FileStream.Read(); would read from a the new position, but it didnt effect the positioning of XmlTextReader.Read(). Even though XmlTextReader is based on the same FileStream. It caused though the last read of the XmlTextReader to validate the xml erroneously (when the xml was actually ok). An alternative is to base a StreamReader on a FileStream. The StreamReader.BaseStream is available for random access, and the StreamReader is there for sequential read. But i think the same problem is there, as when basing the XmlTextReader on the FileStream. As a side thought to the problem, - it could be more easily solved if MicroSoft offered an indexing mechanism (for application purposes) on NTSF files. But this isn't the case. Or if i could load the huge file into a database table, but the requirement is only to use xml files (or flat files), so this isn't an option. This question involves several "technologies". So i am posting it on several newsgroups. Here's a sample of the XML: Each "LogEntry" node is viewed as line of text in a GridView controller. <Logs AtrA="AllTheLogs"> <Log AtrA="log1" AtrB="Machine nr 1"> <LogEntry AtrA="name1" AtrB="time" AtrC="location" /> <LogEntry AtrA="name2" AtrB="time" AtrC="location" /> <LogEntry AtrA="name3" AtrB="time" AtrC="location" /> <LogEntry AtrA="name4" AtrB="time" AtrC="location" /> </Log> <Log AtrA="log2" AtrB="Machine nr 1"> <LogEntry AtrA="name5" AtrB="time" AtrC="location" /> <LogEntry AtrA="name6" AtrB="time" AtrC="location" /> </Log> </Logs> Some test code using XmlTextReader(FileStream) based on a file with the above xml. I used the VS debugger to look into the variables. System.IO.FileStream fs = null; int i = 0; long[] bookMarks = new long[4000]; String[] linesOfText = new String[4000]; byte[] aBuffer = new byte[1000]; char[] charBuffer = new char[1000]; try { fs = new FileStream("c:\\aXMLfile.xml", FileMode.OpenOrCreate); System.Xml.XmlTextReader reader = new XmlTextReader(fs); long lngthOfFS = fs.Length; Boolean a = false; while (reader.Read()) { bookMarks[i] = fs.Position; StreamReader sr = new StreamReader(fs); if (i == 2) { fs.Read(aBuffer, 0, aBuffer.Length); fs.Position = 0; fs.Read(aBuffer, 0, aBuffer.Length); for (int g = 0; g < aBuffer.Length; g++) { charBuffer[g] = (char)aBuffer[g]; } } linesOfText[i] = "Attribute count: " + reader.AttributeCount + ", NodeType: " + reader.NodeType + ", Name: " + reader.Name + ", value: " + reader.Value; a = reader.HasAttributes; if (reader.HasAttributes) { for (int ii = 0; ii < reader.AttributeCount; ii ++) { reader.MoveToAttribute(ii); linesOfText[i] = linesOfText[i] + "Attribute " + ii.ToString() + ":" + ", Name: " + reader.Name + ", value: " + reader.Value; } } i++; } } catch(Exception e) { String message = e.ToString(); } finally { fs.Unlock(0, fs.Length); } Other references: Efficient Techniques for Modifying Large XML Files http://msdn2.microsoft.com/en-us/library/aa302289.aspx XML Reader with Bookmarks http://msdn2.microsoft.com/en-us/library/aa302292.aspx The Best of Both Worlds: Combining XPath with the XmlReader http://msdn2.microsoft.com/en-us/library/ms950778.aspx Comments to references: Helena Kupkova developed a XmlBookmarkReader class (based on XmlReader). But when XmlBookmarkReader sets a bookmark on a read node, it caches it and the following node, to be able to "replay" the bookmark when it is needed. On huge files, an early bookmark will cache the xml content of the file until the applicaiton runs out of memory. Dare Obasanjo XPathReader doesnt avoid a sequential read of the file, testing for each read, for a match for one or more xpaths. For a new XPath, the code would have to seqential reading from the start of the file. -- Regards, Paul Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144856
  - 12
    - Question to the generals in this newsgroup including MSFT's Is this a FrameWork.ADONET or a LINQ newsgroup? As I see so many non LINQ to ADONET questions answered at the moment. Cor Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144843
  - 13
    - Reading a text field How do I get the data out of an MS-SQL Text field efficiently A simple "SELECT [FieldName] FROM [Table]" unfortunately returns a truncated version of the fields contents ( which actually contains an entire book ). I know that your not supposed to do a simple select, but my Google-Fu is weak and I dont know what words to search for. Can anyone supply some hints? Thanks Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144836
  - 14
    - SQL 2005 Error connecting to SQL2000 Hi, I'm connecting to an SQL2000 Server, it runs a very slow SP that takes around two minutes. I've set the command & connection timeout to handle this. It used to work fine but now I get a seemingly unrelated error. I can connect remotely to do simple queries & LINQ queries but the SP doesn't run. Any ideas would be gratefully appreciated Below is the error message: "An error has occurred while establishing a connection to the server. When connecting to SQL Server 2005, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)" Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144830
  - 15
    - Linq SubmitChanges and DataLoadOptions I have some code that has a DataLoadOption to load Master/Detail records. When I update the Master table, the object gets returned but the Details records are not loaded. Is their a work around for this? using (MyDataContext dc = new MyDataContext()) { DataLoadOptions lo = new DataLoadOptions(); lo.LoadWith<Job>(s => s.JobSections); var query = from obj in dc.Jobs where obj.JobID == 1 select obj; job = query.Single(); //yep job object has detail section data dc.SubmitChanges(); //nope job does not have detail section data. } Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144825
  - 16
    - linq combined query I tried to make some complex linq queries easier to read by pulling some of the queries out. This works fine: var qAllJobDescriptions = from j in dc.Jobs select j; var qAllOracleJobCodes = from o in dc.OracleJobCodes select o.JOBCODE; GridView_Ex3.DataSource = from j in qAllJobDescriptions where !(qAllOracleJobCodes).Contains(j.OracleJobCode) select j; This works fine: var qActiveJobDescriptions = from j in dc.Jobs where DateTime.Today >= j.StartDate && (j.EndDate == null || (DateTime.Today < j.EndDate.Value.AddDays(1))) select j; var qActiveOracleJobCodes =""; GridView_Ex2.DataSource = (from j in qActiveJobDescriptions where !(from o in dc.OracleJobCodes where DateTime.Today >= o.DATEFROM && (o.DATETO == null || (DateTime.Today < o.DATETO.Value.AddDays(1))) select o.JOBCODE).Contains(j.OracleJobCode) select new { j.OracleJobCode }) This blows up when I move the where !(....).Contains into its own query. Seems odd because I did a similar thing in the first example. : var qActiveJobDescriptions = from j in dc.Jobs where DateTime.Today >= j.StartDate && (j.EndDate == null || (DateTime.Today < j.EndDate.Value.AddDays(1))) select j; var qActiveOracleJobCodes =from o in dc.OracleJobCodes where DateTime.Today >= o.DATEFROM && (o.DATETO == null || (DateTime.Today < o.DATETO.Value.AddDays(1))) select o.JOBCODE; GridView_Ex2.DataSource = (from j in qActiveJobDescriptions where !(qActiveOracleJobCodes).Contains(j.OracleJobCode) select new { j.OracleJobCode }) ((System.Exception)((new System.Linq.SystemCore_EnumerableDebugView<<string>>(((System.Data.Linq.DataQuery<<string>>)(GridView_Ex2.DataSource)))).Items)).StackTrace at System.Data.Linq.SqlClient.SqlFactory.Member(SqlExpression expr, MemberInfo member) at System.Data.Linq.SqlClient.QueryConverter.VisitMemberAccess(MemberExpression ma) at System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node) at System.Data.Linq.SqlClient.QueryConverter.VisitExpression(Expression exp) at System.Data.Linq.SqlClient.QueryConverter.VisitCast(UnaryExpression c) at System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node) at System.Data.Linq.SqlClient.QueryConverter.VisitExpression(Expression exp) at System.Data.Linq.SqlClient.QueryConverter.VisitBinary(BinaryExpression b) at System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node) at System.Data.Linq.SqlClient.QueryConverter.VisitExpression(Expression exp) at System.Data.Linq.SqlClient.QueryConverter.VisitBinary(BinaryExpression b) at System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node) at System.Data.Linq.SqlClient.QueryConverter.VisitExpression(Expression exp) at System.Data.Linq.SqlClient.QueryConverter.VisitWhere(Expression sequence, LambdaExpression predicate) at System.Data.Linq.SqlClient.QueryConverter.VisitSequenceOperatorCall(MethodCallExpression mc) at System.Data.Linq.SqlClient.QueryConverter.VisitMethodCall(MethodCallExpression mc) at System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node) at System.Data.Linq.SqlClient.QueryConverter.VisitSelect(Expression sequence, LambdaExpression selector) at System.Data.Linq.SqlClient.QueryConverter.VisitSequenceOperatorCall(MethodCallExpression mc) at System.Data.Linq.SqlClient.QueryConverter.VisitMethodCall(MethodCallExpression mc) at System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node) at System.Data.Linq.SqlClient.QueryConverter.VisitContains(Expression sequence, Expression value) at System.Data.Linq.SqlClient.QueryConverter.VisitSequenceOperatorCall(MethodCallExpression mc) at System.Data.Linq.SqlClient.QueryConverter.VisitMethodCall(MethodCallExpression mc) at System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node) at System.Data.Linq.SqlClient.QueryConverter.VisitExpression(Expression exp) at System.Data.Linq.SqlClient.QueryConverter.VisitUnary(UnaryExpression u) at System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node) at System.Data.Linq.SqlClient.QueryConverter.VisitExpression(Expression exp) at System.Data.Linq.SqlClient.QueryConverter.VisitWhere(Expression sequence, LambdaExpression predicate) at System.Data.Linq.SqlClient.QueryConverter.VisitSequenceOperatorCall(MethodCallExpression mc) at System.Data.Linq.SqlClient.QueryConverter.VisitMethodCall(MethodCallExpression mc) at System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node) at System.Data.Linq.SqlClient.QueryConverter.VisitSelect(Expression sequence, LambdaExpression selector) at System.Data.Linq.SqlClient.QueryConverter.VisitSequenceOperatorCall(MethodCallExpression mc) at System.Data.Linq.SqlClient.QueryConverter.VisitMethodCall(MethodCallExpression mc) at System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node) at System.Data.Linq.SqlClient.QueryConverter.ConvertOuter(Expression node) at System.Data.Linq.SqlClient.SqlProvider.BuildQuery(Expression query, SqlNodeAnnotations annotations) at System.Data.Linq.SqlClient.SqlProvider.System.Data.Linq.Provider.IProvider.Execute(Expression query) at System.Data.Linq.DataQuery`1.System.Collections.Generic.IEnumerable<T>.GetEnumerator() at System.Linq.SystemCore_EnumerableDebugView`1.get_Items() Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144823
  - 17
    - Error in field binding when using same table for combobox drop down and lookup Hi I have a sample vs 2008 winform project here; http://www.infovis.biz/TestEMS-vs2800.zip . Please extract it in C:\ folder so the project ends up in C:\Test EMS folder. Please run the project and you will see a data entry form. Use the buttons in the form's bottom area to scroll through the records. Everything works fine. You can even change text in fields and moving away from record will save it. Now go back into project and uncomment line 196 in frmStaff.vb ie Me.txtRate.Text = CStr(DLookup("[Rate]", "[Rates]", "[Rate ID] = """ & txtRateID.Text & """")) Now run the project and scroll through records. Soon you will see that information stops appearing in fields. The purpose of above line is that when user selects a Rate ID from the combobox drop down, the system looks up the corresponding rate amount and fills the Rate field with it. So my question is, why is this lookup causing this problem and what is the correct way to lookup a value and assign it to a bound field without causing this problem? Thanks Regards Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144822
  - 18
    - Update not working I'm developing a Web App in C#. The following method executes without exceptions but the database does not get changed. The data is changed in the record[0] at the point prior to executing the " adapter.Update(record);" instruction. Is there something else I should be doing to insure the update to take effect??? Thanks, Neil protected void UpdateUserFields(String id, String field, String value) { //***********************************************************// ***** Make connection, process request, break connection //*********************************************************** using (OdbcConnection connection = new OdbcConnection(ConnectionBuilder().ConnectionString)) { // ***** Make connection and get dataRows ***** String sql = "select * from Register where Id='" + id + "'"; OdbcDataAdapter adapter = new OdbcDataAdapter(sql, connection); DataSet dataSet = new DataSet(); try { connection.Open(); adapter.Fill(dataSet, "Register"); } catch (Exception ex) { Console.WriteLine(ex.Message); } DataRow[] record = dataSet.Tables["Register"].Select(); if (record.Count() == 0) return; //****** Process update request ****** // Update the cpu id list in the user's registation record if (field=="CpuId") record[0]["CpuId"]=value; //****** Update the data base with changes ****** // Mark the changes for updating record[0].AcceptChanges(); // Update the changes adapter.Update(record); } } Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144817
  - 19
    - Internet - Take Advantage of Multiple Windows When Surfing -- Internet - Take Advantage of Multiple Windows When Surfing SUMMARY: Stop jumping back and forth between index pages by using several browser windows. Why use one web browser window when you can have multiple? If you have an adequate amount of memory, open up several web browsers to maximize your surfing experience. One great way to do this is via a start page. Select a page from where you would like to begin browsing, such as a table of contents or links page. Now, instead of left-clicking on links or entries to view other pages, right-click the links. From the pop-up menu that appears, look for something like "Open in New Window" or "Browse in New Window." This starts up another web browser window with the link you selected, keeping the original page on the screen. http://www.visitbazaar.com VisitBazaar.com has you a browser application which gives the experience of multi window surfing simultaneously, and also increases the internet browsing speed. Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144816
  - 20
    - How to check if SQL Server is local or remote Hello everyone, I have a small c#1.1 app that uses an Oledb connection to connect to SQL Server (2000/2005). What I'd like to know if there is an easy way to understand if the connection points to a local SQL Server or a remote SQL Server... Of course I could inspect the connectionstring and check for (local) or 127.0.0.1 or resolve the machine name... I was just wondering if there is an easier way... TIA Paolo Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144815
  - 21
    - Error : Failed to find or load the registered .Net Framework Data Provider I get the error message "Failed to find or load the registered .Net Framework Data Provider" when I drag database table from database explorer window to Dataset designer window. I also get this error when I click New file/Sql server database. I have Visual Web Developer 2008 Express Edition and 2 instances of ms sql 2005 : developer and express (named .\sqlexpress). Any idea? Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144808
  - 22
    - New db application advise Hi I need to write my first vb.net/sql server app and I just need pointers as to how pros do it. My app is a multi-user apps which needs to refresh from what other users are adding to the backend sql server db. My question is; 1. Do I just drag the fields on to a form and let the vs 2008 generate all code (I understand bindingsource will not automatically show the records added by other user in this technique?), or 2. Write some sort of stored procedures to return one record or some records at a time) at a time and assign manually to the form fields, or 3. Do something else? Thanks Regards Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144806
  - 23
    - Data is different than in database I am using MS Access and VB .NET 2005 (the same problem happens in VB.NET 2008). I am reading from a query using DataReader (the same problem happens if I use OLEDBDataAdapter). When I run the query in Access, the value for Cash = 830.004999999999, SC = 1692.5 and Profit = -862.495000000001. Cash = SC + Profit. But when I read the value from the program, this is what I got: Cash = 830.000000000489 SC = 1692.5 Profit = -862.499999999511. Why this difference and how can I fix it ? Thank you. Here are the codes: Dim m_cmd As OleDb.OleDbCommand Dim m_dr As OleDb.OleDbDataReader Dim sSQL As String m_cmd = New OleDb.OleDbCommand With m_cmd .Connection = adoConOLE .CommandText = "select Cash,Profit from myQuery where Account = '123'" End With m_dr = m_cmd.ExecuteReader() If m_dr.Read Then sSQL = sSQL & " " & m_dr.Item("Cash") --> this returns 830.000000000489 instead of 830.004999999999 when I run it from Access sSQL = sSQL & " " & m_dr.Item("SC") --> this returns 1692.5, which is the same as when I run it on Access sSQL = sSQL & " " & m_dr.Item("Profit") --> this returns -862.499999999511 instead of -862.495000000001 when I run it from Access End If Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144802
  - 24
    - Sync Services for ADO.Net and SQL 2008 Change Tracking, example co I have been searching for a functional example that demonstrates function between these two products for 8 days. I have exchanged emails with two senior guys associate with the Sync Framework team (Steve Lasker and Liam Cavanagh). Steve referred me to Liam and Liam referred me to this sample code: http://msdn2.microsoft.com/en-us/library/cc305322(SQL.100).aspx This code looked like salvation. Unfortunately, I cannot get it to compile on the dev VPC I have dedicated for this purpose. There are versioning issues with the Sync Service for ADO.Net and Sync Framework dlls on the machine. I have uninstalled them and reinstalled them to no avail. I have a message from a great help in another forum who can get the example code to compile in his environment; he told me the version on one of the DLLs he's using and I can't get/locate that version. I have two versions of the binary in question; an older and a seemingly newer version, but no the middle version that works. All of that rambling may be moot. I simply need a functional Sync Services for ADO.Net example that makes use of SQL Server 2008's Change Tracking functionality (brand new in CTP 5). I need to do bi-directional sync'ing from a c# windows app to SQL Server 2008. Any bidirectional/Change Tracking-based example will do, so long as it is functional. I require MS support on this one. If you can refer me to a more accurate place to get timely support, please do so. I can be contacted at uwcanada at gmail com. Thank you in advance Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144792
  - 25
    - Loading a generic collection from a SqlReader? Hi, is there any underlying difference between loading a generic collection from a reader using the two methods: List<User> colUsers = new List<Users>(); while (reader.Read()) { User user = new User(); user.FirstName = (string)reader["FirstName"]; user.LastName = (string)reader["LastName"]; colUsers .Add(user); } ----vs---- while (reader.Read()) { colUsers.Add(new User ( (string)reader["FirstName"], (string)reader["LastName"] )); } Creating the object first and then adding values worked fine. But using the second method by loading the values in the constructor, the colUsers.Count was correct based on the query, but each of the object's properties in the collection were null. it's as if the object's weren't retaining their values or state when added to the collection. Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144790
- Next
  - 1
    - LINQ-to-SQL transaction problem in calculated property I have a DBML object that maps database to objects. In the partial Text class I added a couple of calculated properties. Several of them are dependant on how many child object are related to the current object. To avoid duplicate database calls I got the idea to set local variable _childrenCount in the Text OnLoaded event. partial void OnLoaded() { // ChildrenCount is used in many calculated properties and is therefore set already on Load. using (MyDataContext dc = MyDataContext.CreateInstance()) { _childrenCount = dc.Texts.Where(t => (t.TextIDParent == this.TextID) && (t.TextID != this.TextID)).Count(); } } I found no way to refer to and reuse the current datacontext object to do the call, therefore I created an instance method on the datacontext object to provide a new object. But it really looks like a workaround. The above solution actually worked fine until I added TransactionScope to my code. When a retrieved Text object is involved in a transaction it will fail with the following message: "MSDTC on server XXX is unavailable". When the above event handler is removed everything works fine. I guess the transaction will detect a new datacontext object is called and expect it to take part in the transaction. Actually it should not bother beacuse it is only a passive read. 1) Is it possible to reuse the outer datacontext call for the inner calculation? 2) Can I tell the inner datacontext not to take part in the outer transaction? 3) Is there a better way to set the value of the inner private variable _childrenCount? 4) Should I configure DTC and/or exchange TransationScope with Transaction? Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144785
  - 2
    - The user instance login flag is not supported on this version of S I copied a C# project from one machine to another both XP Pro with VS2005. Then solution compiles but when I run the app I get the error message on the first dataadapter.FILL() command: "The user instance login flag is not supported on this version of SQL Server. " SQLExpress and SQ 2000 is installed, but I am specifiing SQL Express in the connection string see below and the SQL 2000 server is not started. Do I need to uninstall the SQL 2000 server? Shouldn't this work with the SQL 2000 on the same machine? When I just remove the "User Instance =True" from the connection string I still get this message. What am I doing wrong? <connectionStrings> <add name="CMMB1.Properties.Settings.CallMasterSQLConnectionString" connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename="C:\Program Files\CALLMaster\Data\CallMasterSQL.mdf";Integrated Security=True;Connect Timeout=30;User Instance=True" providerName="System.Data.SqlClient" /> </connectionStrings> -- Thanks Morris Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144779
  - 3
    - DataColumn DataType Conversion I have an application that takes a DataTable full of string values and then inserts them into a SQL Table with SqlBulkCopy. I have one unresolved issue. The values in the DataTable are all strings, but the fields in the SQL Table, are not all string types. So we have the following dilemma: Converting the DataType of a DataColumn in a DataTable that is already populated is illegal. I certainly can use the Expression field of the DataColumn class and create a new DataColumn with the appropriate DataType, but I cannot leave the original column as all columns are used in SqlBulkCopy and removing the original column invalidates the expressions. And so: Is there any way to create a new DataTable, by copying the Columns that don't need conversion and the values in the Expression columns, without going value by value through the whole table? Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144776
  - 4
    - Get return code from SQL Server Sproc? Say I have a procedure that returns a return code like the following... CREATE PROCEDURE TestProc AS BEGIN SET NOCOUNT ON; SELECT * FROM MyTable; RETURN 10 END And I execute that in a sql command object, how does my client application get the return code back? Which in this case is 10.. thanks! Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144772
  - 5
    - Obtaining a List of Databases I can use the SqlDataSourceEnumerator to get a list of SQL Server instances. How do I obtain a list of databases in a given SQL Server instance? Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144764
  - 6
    - Help with multiple connector/table query As a newbie to ADO.NET I am struggling with the following: I have an ODBC data table that I want to use a source for updates to a SQL server table, I envisage the sql query having the following structure:- INSERT INTO SQL_TABLE FROM SELECT ODBC_TABLE WHERE ODBC_TABLE.KEY NOT IN (SELECT SQL_TABLE.KEY FROM SQL_TABLE) How do I do this in ado.net if a sql query is run against a specific connection object? Hope the above makes sense. Help greatly appreciated. Regards, Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144755
  - 7
    - OracleClient, Oracle 10g, Connection failure Hi, I'm trying to connect to an Oracle database via a .NET web service running in IIS on a Windows 2000 server. I am using the OracleClient (System.Data.OracleClient) provider . When I call connection.Open() I get the following error - 'System.Data.OracleClient requires Oracle client software version 8.1.7 or greater' The Oracle 10 client is installed on the box as well as .NET framework V 2.0. Any ideas as to why this is happening? Do I need to install something else? Many thanks, Dav Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144754
  - 8
    - Connection Open Error Hi, Below is the code written for opening a sql server connection and database transactions. private SqlConnection _mConnection; private SqlCommand _mCommand; private SqlTransaction _mTransaction; public SqlDataAdapter CreateDataAdaptor(string comText, CommandType ComType, string Attribute) { try { _mCommand = new SqlCommand(); _mConnection = new SqlConnection(ConnectionString(Attribute)); _mCommand.Connection = _mConnection; _mCommand.CommandType = ComType; _mCommand.CommandText = comText; if (_mConnection.State != ConnectionState.Open) { _mConnection.Open(); } SqlDataAdapter da = new SqlDataAdapter(_mCommand); return da; } catch (Exception ex) { throw ex; } finally { if (_mConnection.State == ConnectionState.Open) { _mConnection.Close(); _mConnection.Dispose(); _mCommand.Dispose(); } } } public void Insert(string comText, Parameters Params, CommandType ComType, string Attribute) { try { _mCommand = new SqlCommand(); _mConnection = new SqlConnection(ConnectionString(Attribute)); _mCommand.Connection = _mConnection; _mCommand.CommandType = ComType; _mCommand.CommandText = comText; //_mCommand.Transaction = _mTransaction; if (_mConnection.State != ConnectionState.Open) { _mConnection.Open(); } if (ComType == CommandType.StoredProcedure) { if (Params != null) { foreach (Parameter oParam in Params) { _mCommand.Parameters.AddWithValue(oParam.Name, oParam.Value); } _mCommand.ExecuteNonQuery(); } } else { _mCommand.ExecuteNonQuery(); } } catch (Exception ex) { throw ex; } finally { if (_mConnection.State == ConnectionState.Open) { _mConnection.Close(); _mConnection.Dispose(); _mCommand.Dispose(); } } } Though am opening and closing the connection properly,sometimes i am getting this error "Connection is already open"."Please close the connection".(when there are a no of users logon to the application) Can someone tell me whether i am doing something wrong. Romi Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144747
  - 9
    - Connection Open Error Hi, Below is the piece of code i am using for my connection object & database transaction. private SqlConnection _mConnection; private SqlCommand _mCommand; private SqlTransaction _mTransaction; public SqlDataAdapter CreateDataAdaptor(string comText, CommandType ComType, string Attribute) { try { _mCommand = new SqlCommand(); _mConnection = new SqlConnection(ConnectionString(Attribute)); _mCommand.Connection = _mConnection; _mCommand.CommandType = ComType; _mCommand.CommandText = comText; if (_mConnection.State != ConnectionState.Open) { _mConnection.Open(); } SqlDataAdapter da = new SqlDataAdapter(_mCommand); return da; } catch (Exception ex) { throw ex; } finally { if (_mConnection.State == ConnectionState.Open) { _mConnection.Close(); _mConnection.Dispose(); _mCommand.Dispose(); } } } public void Insert(string comText, Parameters Params, CommandType ComType, string Attribute) { try { _mCommand = new SqlCommand(); _mConnection = new SqlConnection(ConnectionString(Attribute)); _mCommand.Connection = _mConnection; _mCommand.CommandType = ComType; _mCommand.CommandText = comText; //_mCommand.Transaction = _mTransaction; if (_mConnection.State != ConnectionState.Open) { _mConnection.Open(); } if (ComType == CommandType.StoredProcedure) { if (Params != null) { foreach (Parameter oParam in Params) { _mCommand.Parameters.AddWithValue(oParam.Name, oParam.Value); } _mCommand.ExecuteNonQuery(); } } else { _mCommand.ExecuteNonQuery(); } } catch (Exception ex) { throw ex; } finally { if (_mConnection.State == ConnectionState.Open) { _mConnection.Close(); _mConnection.Dispose(); _mCommand.Dispose(); } } } Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144746
  - 10
    - Handling concurrency violations Hi I have developed the following logic to handle db concurrency violations. I just wonder if someone can tell me if it is correct or if I need a different approach.Would love to know how pros handle it. Thanks Regards Dim dc As DataColumn Dim drCache As DataRow Dim drCurrent As DataRow Try ' Attempt the update daContacts.Update(ds.Contacts) Catch Ex As DBConcurrencyException ' First - cache the row drCache = ds.Contacts.NewRow() For Each dc In ds.Contacts.Columns If Not dc.ReadOnly Then drCache(dc.ColumnName) = Ex.Row(dc.ColumnName) End If Next ' Refresh from database daContacts.Fill(ds.Contacts) ' Position to the faulted row drCurrent = ds.Contacts.Rows.Find(Ex.Row("ID")) ' Apply User Changes For Each dc In ds.Contacts.Columns If Not dc.ReadOnly Then drCurrent(dc.ColumnName) = drCache(dc.ColumnName) End If Next ' Save again daContacts.Update(ds.Contacts) End Try Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144743
  - 11
    - Connection Pooling, REVERT & "Connection Reset" in .NET 2.0 SP1+ Hi, My company is building a multi-tenant internet-facing web app in ASP.NET / SQL 2005. We can't therefore use NT authentication, and must use our own web forms authentication, but still need to use SQL's "Database User"-based security so that we can encapsulate security in stored procs etc by checking user_id() - we create these DB users (for each web end user) "WITHOUT LOGIN" and multiplex through a single proxy account. Legacy reasons mean we can't design around this requirement. We have used Enterprise Library to standardize DB access, and implemented a new Database Provider to implement the security requirement above while still allowing scalability through connection pooling: when the Connection's open event is called, we connect to SQL Server using a proxy account and call "EXECUTE AS" the desired db user, changing the connection context. We store the 'cookie' returned from this call against the connection SPID so that on subsequent Connection Open (which gives us a connection from the pool which might have already been set to another user's context) we check the SPID to see if there's already cookie, use REVERT WITH COOKIE to revert to proxy account, before calling "sp_reset_connection" which resets the connection and we can set to new user context. Why do we try to REVERT on connection Open? We would rather REVERT just before connection close but we cannot control when this occurs (datareader consumers of the connection, which we cannot control, may close the connection automatically) or hook into an event (statechanged only tells us AFTER the connection is closed - cannot reopen!) This all required us to use the "Connection Reset=false" connection string setting, which ensures that sp_reset_connection (SQL internal SP) is not called automatically because we must REVERT BEFORE this proc is called otherwise the connection is dropped by SQL server because the reverting context is different to original proxy login. This slightly complicated (but quite compact and elegant) solution works fine on .NET 2.0 RTM. BUT it seems that from .NET 2.0 SP1 onwards, the "Connection Reset" connection string API has been deprecated! This means the connection pooling mechanism ignores the setting and tries to execute "sp_reset_connection" on each connection open as a different context than the original login and SQL server duly kills the connection (and crashes the app). In short, I've run out of options for REVERTing the connection just before it's closed. The connection statechange event is too late and binding to 3rd party controls means they may use datareaders which automatically close the connection before I can intervene. The only relevant Microsoft documentation I have found (on App Roles and connection pooling) states: ".. if pooling is enabled, the connection is returned to the pool, and an error occurs when the pooled connection is reused. If you are using SQL Server application roles, we recommend that you disable connection pooling for your application in the connection string." GRRR! How does Microsoft expect us to build scalable applications with the features specifically designed for it (connection pooling, EXECUTE AS + REVERT) if these features no longer work together? Hosting this app without connection pooling is unacceptable, and I don't want to have to rewrite the entire security infrastructure. It seems my only option is to use compile my own version of Enterprise Library, implementing my own Connection object which can intercept the Close method calls - this is neither elegant, nor maintainable, and I'm hoping that someone has a better idea? If there _is_ a way to grab an event on the connection just before it closes, that would be perfect... Anyone? Many thanks for your time, and any help you can give... Simon RIP "Connection Reset": http://msdn2.microsoft.com/en-us/library/system.data.sqlclient.sqlconnectionstringbuilder.connectionreset.aspx Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144741
  - 12
    - Getbytes usage from VS 2003 to VS2005 When accessing a BLOB from a DB using getbytes, 0 bytes are returned. The same thing worked with VS2003. The recent environmental change was from VS2003 to VS2005 and also from .NET 1.1 to .NET 2.0. /* Here is the function that reads the blob from the db */ private bool GetImageSeq(ref byte[] SeqImage,string PatId,string AdmDate,int ImgSeq,int SeqSz) { long RtnBytes=0,startIndex=0; string MyStr="",SqlStr=""; SqlStr = "SELECT binimage FROM PUB.Images WHERE patid = '" + PatId + "' AND admdate = '" + AdmDate + "' AND imgseq = '" + ImgSeq.ToString() + "'"; OdbcConnection ImgConn = new OdbcConnection(Session["ConnStr"].ToString()); OdbcCommand ImgSel = new OdbcCommand(SqlStr,ImgConn); ImgConn.Open(); OdbcDataReader ImgRead; if (ImgConn.State.ToString() != "Open") return(false); else { try { ImgRead = ImgSel.ExecuteReader(CommandBehavior.SequentialAccess); MyStr = ImgRead.FieldCount.ToString(); //ImgRead.RecordsAffected.ToString(); ImgRead.Read(); /* with .net 1.1, RtnBytes equaled the blob size. In .net 2.0, it is zero bytes getting returned. */ RtnBytes = ImgRead.GetBytes(0,startIndex,SeqImage,0,SeqSz); ImgRead.Close(); } catch (Exception ex) { MyStr = ex.Message; } } ImgConn.Close(); return(true); } Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144736
  - 13
    - Update query that won't take DBNull I have a stored procedure that I let the wizard create a function in the QueriesTableAdapter class. Some of the parameters to the stored procedure clearly allow for nulls (AllowDBNull) but somehow the wizard refused to add the Global.System.Nullable(Of String) to the generated function's parameter list. Now I can't use the function if the parameter is DBNull.Value. Can I go and edit the Designer.vb manually or is there a way to cause the wizard to recognize that the function should make the parameter Nullable(Of Type)? -- Michael Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144735
  - 14
    - Restore.Abort (SMO) throws Exception and Cannot Delete Database Using Restore.SqlRestore (synchronous method call) followed by calling Restore.Abort causes the following excepion to be thrown: Restore failed for Server 'localhost\SQLExpress'. Operation cancelled by user. Then tried to delete database with: Server srv = new Server("localhost\SQLExpress") srv.KillDatabase("MyDatabase") Another exception was thrown shown below: Kill database failed for Server 'localhost\SQLExpress'. ALTER DATABASE is not permitted while a database is in the Restoring state. ALTER DATABASE statement failed. However I was able to delete database using SQL Server Manager Studio Express. In addition when viewing the database in SQL Server Manager Studio Express the database name looked like this: "MyDatabase(Restoring...)" It is as though the restore never completed. Does anyone know why this would happen and what is the work around to get the Restore.Abort to work properly? Thanks. Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144732
  - 15
    - Databinding en un Combobox Hi, i am using a list named ListaCombo to populate a combo box with a query, but when i execute the code, comboBox1.DisplayMember = "Display"; it thows a "The connection is already Open (state=Open)" error messages. anyone can give me idea? thanks //TextDate.Text = "Hoy"; mySqlConnection = new SqlConnection(System.Configuration.ConfigurationManager.AppSettings.Get("ConnectionString")); DateTime Date1 = System.DateTime.Now.AddDays(0); string Day = System.Convert.ToString(Date1.Month); string Month = System.Convert.ToString(Date1.Day); string Year = System.Convert.ToString(Date1.Year); string cadDate = Day +"/"+ Month +"/"+ Year; TextDate.Text = cadDate; // Cargando ComboBox SqlDataReader myReader = null; SqlCommand mySqlCommand = new SqlCommand("select zon_cve, zon_Nombre from Zona", mySqlConnection); try { mySqlConnection.Open(); myReader = mySqlCommand.ExecuteReader(CommandBehavior.CloseConnection); ArrayList ListaCombo = new ArrayList(); while (myReader.Read()) { //comboBox1.Items.Add(new MyListItem(myReader["zon_cve"].ToString(), myReader["zon_Nombre"].ToString())); ListaCombo.Add(new MyListItem(myReader["zon_cve"].ToString(), myReader["zon_Nombre"].ToString())); } MessageBox.Show("All names loaded successfully!"); // Here, the code generate a error, already open! *** comboBox1.DataSource = ListaCombo; comboBox1.DisplayMember = "Display"; comboBox1.ValueMember = "Value"; } catch (Exception ex) { MessageBox.Show("Error occurred: " + ex.Message); } finally { if (myReader != null) myReader.Close(); } myReader.Close(); Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144727
  - 16
    - Guarantee read lock in transaction? I have a SQL table where the PrimaryKey column ID is a long. There is a ForeignKey relation from column ParentID back to the same table to track relation. Default for new records is always to relate back to itself. I don't really care what value is used for ID on new records, but as I need to have the same value on ParentID as in ID I have so far created the value manually based on the current used max value of all records. Problem is I would like to guarantee the same value is not used for two different inserts. Is it possible to guarantee read lock in a transaction? I am using LINQ-to-SQL and planned to use TransactionScope mechanism. But then it struck me that this solution might not be safe for reads. I would like to avoid two subsequent inserts to read the same current-max-used-ID of my table which would mean they calculated the same new ID for the PrimaryKey. Is there a better way to accomplish the same thing? Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144725
  - 17
    - Compacting and repairing access 2000 db Hi Is it possible to compact and repair an external access 200 database via code? Thanks Regards Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144716
  - 18
    - LINQ with switch statement Hi, I'm trying to use a swithc statement in a LINQ query but its not ahppy at all. Any ideas as to the correct way to go about this? Many thanks for any ideas Ant Below is the statement: var resultSet = from p in db.Projects where p.ProjectCode == textboxProjectCode.Text && p.RevisionStatusCode == 'A' select new { p.ProjectCode, p.RevisionNum, "StatusCode" = switch (p.StatusCode) { case 'I': "Inactivated"; break; case 'E': "Engaged"; break; case 'C': "Closed"; break; case 'P': "Planned"; break; default: "default"; break; }, p.RevisionName, p.LastUpdateUserID, p.LastUpdateDate }; Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144714
  - 19
    - dbml metadata Is their a way to get the dbml metadata at runtime. For example I would like to see the datatype and length for the LastName field. Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144707
  - 20
    - drop column via ODBC with "active relation" Hi, Situation: * Access to a MS Access DB via ODBC * Two columns of two tables a related (checked with MS Access GUI) * I want to delete (drop) one colum of one table (which is not a key column) but related to the other table code: commandstr="ALTER TABLE "+Name+" DROP COLUMN "+scheme.ColumnName; //MLHIDE cmd=AdoProviderFactory.GetCommand(commandstr,m_DB.Connection,m_DB.ProviderType); try { cmd.ExecuteNonQuery(); } Since there is a relation I get an error message - OK. 1. How can I get a list of relations via ODBC.NET. 2. How can I delete a relation All the example I found are working on a dataset. But if I fill a dataset via a ODBC adaption there a no relations... commandstr += "SELECT * FROM \"" + TableName + "\""; // do I have to change this, table is the one I want to drop a column cmd = AdoProviderFactory.GetCommand(commandstr, m_DB.Connection, m_DB.ProviderType); adapter.SelectCommand = cmd; try { DataSet destdataset = new DataSet(); adapter.Fill(destdataset); Maybe I have to use the connection.GetSchema("WHATTOFILLHERE") methods to get Relations via ADO .NET? thx in advance Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144706
  - 21
    - Query Parameter prefix in Oledb I am trying to create a parametrized query based on City on the customers table in Northwind.mdb. The sql version on Northwnd.mdf works fine using @City in the query, but when I try to create it for the access dataset, it puts single quotes around the '@City'. Is there another character one has to use for access? I am using Vb.net 2008 Thanks for any help, Peter Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144701
  - 22
    - Using sender object in event handler Hi, I'm tring to use the event handler in the statement completed event of a command object to retrieve the value of the output parameter passed from the SP. When I try to do this, I get an 'Object referece not set to an instance of an object' What is going wrong here? Isn't sender the Command object? Shouldn't it have a collection of the parameters & the value of the output param? Below is what I'm trying to so in the event handler. I've broken up the instantiation of the command obj to make it simpler. void commandBackup_StatementCompleted(object sender, StatementCompletedEventArgs e) { // cast the sender obj to a command obj SqlCommand commandResult = ((SqlCommand)sender); // get the value of the output parm string resultString = commandResult.Parameters["@ResultString"].Value.ToString(); // display the value textboxCompleted.Text = resultString; } many thanks for any help anyone can provide Ant Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144700
  - 23
    - Passing values to event parameters Hi, I'm using the StatementCompleted event of the Command object & would like to pass to it the output value of a stored proc. Can this be done without writing a new delegate for the event? Can I somehow use the sender object or the StatementCompletedEventArgs to do this? This is the event: commandBackup.StatementCompleted += new StatementCompletedEventHandler(commandBackup_StatementCompleted); This is the event handler: void commandBackup_StatementCompleted(object sender, StatementCompletedEventArgs e) { // someting like Response.Write( someObj.ReturnValue.ToString() ); } How can this be done? Many thanks for any ideas on this Ant Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144698
  - 24
    - Organize Data in a DataSet Hello I'm busy with a client application which is working on client-data. Client data are spread over several 1:n tables in the database. How should I organize data in the dataset(s) ? 1) Create one dataset for each client with the tables which select only the data specific to this client. 2) Imitate the table structure and relations of the database, means: one dataset including one table for all the clients, one table for all the addresses, one table for all the bankaccounts etc.). What are the advantages and what are the disadvantages or is there only one way to do it? Thank you Sincerely Lore Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144697
  - 25
    - Nested Updates using SQLCLIENT classes I worte a routine in VB.NET 2005 + SQL Server 2005 that operates on a single table. I loop through 10 "LEVELS". For each of these "LEVELS" I extract n "PATTERNS" where n could be between 700 and 2000. For each of those LEVEL+PATTERN, I select matching records and splite them up into two DataSets - "dataSetComeplete" and "dataSetEmpty". Based on deeper patterns found in "dataSetComeplete", I edit fields in "dataSetEmpty". Finally, I update the "dataSetEmpty", using a sqlAdapter and its updateCommand properties. This update is done withn a sqlTransaction. Once the Update is successful, I dispose the datasets and set them to nothing, before processing the next LEVEL+PATTERN. The program works - but slows down as the process continues, till it hangs compeltely. On the task manager, I see that the Mem Usage keeps on increasing till it increasese no more. I can manually select ant ONE LEVEL and the program works, though slowing down. Sometimes I can get through two LEVELS if the number of patterns are not large. I can write rather large queries in SQL Server - Query Analyzer, but have never written loops, cursors and case statements. Here are my questions - I know without seeing the code it might be a bit difficult - but this is a ADO forum and I am not expecting any help in a VB.NET perspective. 1. From what I explained, does it feel that I am approaching the solution in a wrong way? 2. Can this algorith be implemented in T-SQL? I have never used Loops or Cursors or Transactions and Rollbacks in T-SQL. 3. Is a CLR stored procedure a better approach? 4. For those of you who recommend T-SQL, what/which literature can you refer me to that shows such Iterations, Loops, Cursors, Updates, Transactions etc. Also, how would you monitor the process? There are no progress bars :) or Threads. I am totally stuck and need to run this process ASAP. Any help would be much appreciated. Tag: Microsoft architect to discuss LINQ, ADO.NET Entity Framework & Data Tag: 144696

The program for DataServices World (June 24, New York City) has been
announced. The conference includes a distinguished lineup of speakers
from BEA, Blue Cross/Blue Shield, IBM, iWay Software, Microsoft,
Morgan Stanley and Sun Microsystems.

Mike Pizzo is the lead architect for Microsoft's data access and data
programmability initiatives. He's been responsible for developing the
ODBC Cursor Library, OLE DB, ADO and ADO.NET.

At DataServices World, Mike Pizzo will speak about LINQ, ADO.NET
Entity Framework and ADO.NET Data Services. He will also participate
in a Data Access and Data Services Workshop with Dr. Michael Carey
(BEA Systems) and Dr. Carlo Innocenti (DataDirect Technologies).

http://dataservicesworld.sys-con.com/general/session0608.htm

"LINQ and ADO.NET Entity Framework and Data Services for the Web"
When: June 24, 2008 (2:00 - 2:50 pm)
Where: Roosevelt Hotel, 45th and Madison Avenue, New York City

"The ADO.NET Entity Framework raises the level of abstraction for data
programming. It is the evolution of ADO.NET that allows developers to
program in terms of the standard ADO.NET abstraction or in terms of
persistent objects (ORM) and is built upon the standard ADO.NET
Provider model. The Entity Framework introduces a set of services
around the Entity Data Model (EDM) (a medium for defining domain
models for an application).

The goal of ADO.NET Data Services is to enable applications to expose
data as a REST-based data service that can be consumed by Web clients
within a corporate network and across the Internet. The data service
is reachable over HTTP, and URIs are used to identify the various
pieces of information available through the service. Interactions with
the data service happens in terms of HTTP verbs, such as GET, POST,
PUT, and DELETE, and the data exchanged in those interactions is
represented in simple formats, such as AtomPub and JavaScript Object
Notation (JSON). "

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