DataColumn.Expression questions

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 - test test Tag: DataColumn.Expression questions Tag: 73704
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 - Long-Running DataSet.Fill Ties-Up System Hi, Here's my situation. I developed a Microsoft Access query that polls a remote Intersystems Caché system where all my data resides. Access has a few features I prefer to use, in particular some agregate queries I'd find difficult to replicate on my Caché system. Here's an example of one query: PARAMETERS [@qpar_Start_Date] DateTime, [@qpar_End_Date] DateTime; SELECT SYSTEM_R001_Summary_Data_LIV.Buyer_ID, Count(SYSTEM_R001_Summary_Data_LIV.Buyer_ID) AS [Count] FROM SYSTEM_R002_Line_Detail_LIV INNER JOIN SYSTEM_R001_Summary_Data_LIV ON SYSTEM_R002_Line_Detail_LIV.Line_KeyTo_R001_Summary_Data = SYSTEM_R001_Summary_Data_LIV.Summary_Data_R001_Key WHERE (((SYSTEM_R001_Summary_Data_LIV.PO_Date)>=[@qpar_Start_Date] And (SYSTEM_R001_Summary_Data_LIV.PO_Date)<=[@qpar_End_Date]) AND ((SYSTEM_R002_Line_Detail_LIV.Item_Number) Is Not Null)) GROUP BY SYSTEM_R001_Summary_Data_LIV.Buyer_ID; I use this query as the datasource for another query. Anyhow, suffice to say that I'm heavily invested in MS-Access for performing local queries and I'm not likely to change that anytime soon. These Access-based queries are bound to some ASPX files which users interface with through our intranet website. In this particular case, the parameters in the query (above) are filled based on data that comes from the web site. All this works very well, with one exception: The user submits the form that executes the code-behind. This starts a process whereby the query is run by way of OleDbDataAdapter. A DataSet is filled, and then further things occur depending on the result of the data. The problem is, when the user launches the query, every other OleDbDataAdapter call stalls until the first one finishes. Another problem that I believe is related is that I can't launch more than one query at a time. Here's a simplified bit of code that illustrates the problem. For the sake of the example, this method would be called by a Button_Click event: Private Sub POsByBuyerUncat() Dim oDs As New System.Data.DataSet Try With oDaPOsByBuyerUncat .SelectCommand.Parameters("[@qpar_Start_Date]").Value = _ Convert.ToDateTime(tbStartDate.Text) .SelectCommand.Parameters("[@qpar_End_Date]").Value = _ Convert.ToDateTime(tbEndDate.Text) .Fill(oDs, "POsByBuyerUncat") End With Catch ex As Exception lblRuntimeError.Text = ex.ToString Finally If Not oDaPOsByBuyerUncat Is Nothing Then oDaPOsByBuyerUncat.Dispose() oDaPOsByBuyerUncat = Nothing End If If Not oDs Is Nothing Then oDs.Dispose() oDs = Nothing End If End Try End Sub The problem occurs when the .Fill executes. No other .Fill statements can run on the same IIS machine while the .Fill is running. That includes OleDb calls in other IIS applications, in other .MDB files, and so forth. My remote Caché system is still running fine, and will gladly run all kinds of other jobs so I don't think it's responsible. I have toyed with ODBC Pooling, multithreading, file permissions, and many other combinations of factors but I can't figure it out. Has anyone ever seen this? And if so, how do you fix it? Please reply, either to this newsgroup or by e-mail at David.PyperDontSpamMeMUHC.McGill.CA. David Tag: DataColumn.Expression questions Tag: 73702
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 - General Functions for Using ADO.NET Hi, all, I wrote the following 3 functions in VB.NET. I think it might be useful for programmers new to ADO.NET. You just include this in a VB module. Then it can be accessed in whole project. These functions are for sql server. You can easily modify them for oledb. Bin Song, MCP 'Definition of CONNECTION_STRING Public Const CONNECTION_STRING = "data source=MYSERVENAME;initial catalog=MYDATABASENAME;user id=MYUSERNAME;password=MYPASSWORD;" 'Function to return a dataset 'Syntax: Dim ds as DataSet = GetDataSet("Select * From tblCustomer") Public Function GetDataSet(ByVal sqlSelect As String) As DataSet Dim sqlCnn As SqlConnection Dim sqlAdp As SqlDataAdapter Dim sqlDst As DataSet Try sqlCnn = New SqlConnection(CONNECTION_STRING) sqlCnn.Open() sqlAdp = New SqlDataAdapter(sqlSelect, sqlCnn) sqlDst = New DataSet() sqlAdp.Fill(sqlDst) GetDataSet = sqlDst sqlAdp.Dispose() sqlCnn.Close() sqlCnn.Dispose() Catch eGetDataSet As Exception Throw eGetDataSet End Try End Function 'Function to return a data reader 'Syntax: Dim ds as sqlDataReader = GetDataReader("Select * From tblCustomer") Public Function GetDataReader(ByVal sqlSelect As String) As SqlDataReader 'Close the datareader after Using this function to get a datareader Dim sqlCnn As SqlConnection Dim sqlCmd As SqlCommand Try sqlCnn = New SqlConnection(CONNECTION_STRING) sqlCnn.Open() sqlCmd = New SqlCommand(sqlSelect, sqlCnn) GetDataReader = sqlCmd.ExecuteReader (CommandBehavior.CloseConnection) Catch eGetDataReader As Exception Throw eGetDataReader End Try End Function 'sub to execute a data process query 'Syntax: ExecNonQuery("Delete * From tblCustomer") Public Sub ExecNonQuery(ByVal sqlNonQuery As String) Dim sqlCnn As SqlConnection Dim sqlCmd As SqlCommand Try sqlCnn = New SqlConnection(CONNECTION_STRING) sqlCnn.Open() sqlCmd = New SqlCommand(sqlNonQuery, sqlCnn) sqlCmd.ExecuteNonQuery() sqlCmd.Dispose() sqlCnn.Close() sqlCnn.Dispose() Catch eExecNonQuery As Exception Throw eExecNonQuery End Try End Sub Tag: DataColumn.Expression questions Tag: 73699
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 - vb.net MDI multiple db connections? I have multiple forms that get shown when the users clicks on a button. Each child form has data on it the is recieved from the same database but from different tables. My problem is that I can't get this to work without adding a new db connection on each form. I've tried jsut adding a dataset on the new form but it automatically creates a new db connection for it. It doesn't seem very elegant to have multiple connection to the same DB in one project. I'm new at programming so I was hoping for a simple solution. Thank you Tag: DataColumn.Expression questions Tag: 73698
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 - Detecting and counting changes in a dataset I have a dataset which consists of a main table and a bunch of child tables. I want, firstly, to be able to detect if a particular record has changed, but is there an easy and quick way to tell if the children of a datarow in the parent table have been updated without iterating through all the relationships and checking each one? Currently I have this: public bool HasChanges { get { DataRowView drv = (DataRowView)database[index.Position]; bool changed = (drv.Row.RowState == DataRowState.Modified); foreach (DataRelation rel in database.Data.Relations) { if (changed) break; if (rel.ParentTable == database.Data.Tables["tblMain"]) { DataRow[] child = drv.Row.GetChildRows(rel); foreach(DataRow r in child) { changed = changed | r.RowState == DataRowState.Modified; if (changed) break; } } } return changed; } } Which even with the breaks, which will let the program get out early once it's found one change, still seems like it's horribly inefficent, especially since most of the time there really won't be any changes. I want to be able to display on my form (which shows one record from the main table plus info from the child table) if this record has changed since being loaded from the database, so I need to do this everytime the user navigates to a new record in the database. Any ideas? My other, related, question is how can I count how many records have been changed? I can use GetChanges on the parent table and to get changes there and then use GetChanges on all the child tables too. But if I add them together I'm likely to overcount some records (where both the parent and the child have been changed). Is there an efficient way to deal with this? This is less of an issue than the first case since I don't expect to need to get that number very often. Any insight here is most welcome! Thanks Tag: DataColumn.Expression questions Tag: 73685
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 - Problem viewing XML file in VS.NET 2002 I have an XML file (data and schema) created programatically from a DataTable. I need to open this file in VS.NET and view it in the data view (grid view). When I open the file the first time, this works perfectly well. However, once I close it (no edits) and try to open again, VS gives an error as follows: "Although this XML document is well formed, it contains structure that Data View cannot display. Column requires a valid Data Type." The weird thing is that this still happens even when I make the newly created file read only. It opens in Data View the first time, then it it fails after that. I don't see how the file could change given that it is read only. BTW, all columns are typed. Some are typed as enums we have defined. But if this was a problem, it seems the file wouldn't open in Data View even once. It opens fine the first time. I can regenerate the same file, and it again opens fine the first time it is opened. Also, I set the read only property immediately (before the file is ever opened.) Anyone have any ideas what is causing this? Thanks! Tag: DataColumn.Expression questions Tag: 73683
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 - sqlConnection if i open a connection and then open a datareader off that connection. then loop through the datareader attempting to perform updates through the same connection, then i get an error "There is already an open DataReader associated with this Connection which must be closed first." oh and the there is a transaction based on the connection. should i maybe use a dataset ? dan Tag: DataColumn.Expression questions Tag: 73674
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 - Import text file to access db table (OleDB, ADO, ADO.NET) The question of how to import a text file into the database table has been asked many times. The code that suits me was given by Paul Clement is the following: Sub ImportTextToAccessADO() Dim cnn As New ADODB.Connection Dim rs As New ADODB.Recordset Dim sqlString As String cnn.Open _ "Provider=Microsoft.Jet.OLEDB.4.0;" & _ "Data Source=e:\My Documents\DB1.mdb;" & _ "Jet OLEDB:Engine Type=4;" sqlString = "SELECT * INTO [tblSample2] FROM [Text;HDR=NO;DATABASE=e:\My Documents\TextFiles].[Sample2.txt]" cnn.Execute sqlString cnn.Close End Sub It works great but only if the table doesn't exist. My questions are how to do this if the following table already exists. Will bulk Insert like this work or do I have to use adapter to fill a dataset and then insert into the table row by row. Also how can I check if the table exists then I delete it and create a new one but with the same schema as it had before. Appying the above code to the table that doesn't exist creates a new table with columns labelled F1, F2, etc. How do I create custom columns? I would greatly appreciate any input on this (preferably using .NET). Thank you. Tag: DataColumn.Expression questions Tag: 73672
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 - Execute Non Query Error I am having a problem with ExecuteNonQuery. I have this code: Try strsql = "Insert into [Action] values (" & EndItem.intItemIdentifier & ", " & intActionIdentifier & ", '" & strOrg & "', '" & strStat & "', '" & strStatDate & "', '" & strDesc & "', '" & strTake & "')" Dim cmd As New OleDbCommand(strsql, conn) cmd.ExecuteNonQuery() Catch oledbExc As OleDbException MessageBox.Show(oledbExc.ToString, _ "", MessageBoxButtons.OK, MessageBoxIcon.Error) Catch ex As Exception MessageBox.Show(ex.Message, "", _ MessageBoxButtons.OK, MessageBoxIcon.Error) End Try I get this error message: ExecuteNonQuery requires an open and available Connection. The connection's current state is closed. Yet, I have the connection open at the top of the form and have used it in other instances and it runs perfectly. Public Class ActionEdit 'Inherits System.Windows.Forms.Form Inherits System.Windows.Forms.Form 'Public Shared CriticalParts As Form Public Shared conStr As String = "Provider=Microsoft.JET.OLEDB.4.0;data source=c:\\CPRdatabase.mdb" ' Create connection object Public Shared conn As OleDbConnection = New OleDbConnection(conStr) I am not sure what I am missing that gives me an error here and not anywhere else in my form. Thanks in advance! Elena Tag: DataColumn.Expression questions Tag: 73671
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 - Event handling Hi. I wrote simple C# app, that connects to SQL Server 2000 DB using ADO.NET. I want to monitor inserts to specified table from my app. That is, when someone inserts a row [or entire rowset] to this table, i want to catch this "event" and handle it [rather, i want to get the inserted data]. In old C, this was done with extended stored procedures and system events. Is there any easier way to do this in C# and ADO.NET? Thanks for answer. Regards Marek Samaj Tag: DataColumn.Expression questions Tag: 73670
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 - (newbie) SQL help and how to store it Hi- this is not a complicated question and probably get's asked often.... with that said, here is what I am trying to do. I have 3 tables table1 (products) ProdId ProdName ProdParentId table2 (faq_categories) CatId ProdId CatName table 3 (faq_main) FaqId CatId Question Answer What I want to do is get join all the "faq_categories" that match certain criteria in "products", then join all the "faq_main" that match the relevant faq_categories" Maybe it will make more sense if I show you how I would like to render the data Product1 Category 1 Q:asdasd A:asdagt345dfg Category 2 Q:asdflwfybsdf A:adkbafj Product2 Category 3 Q:asdfhkasfsd A:sdfh34hfsdf So, with that said... how do I do this? Is there a way to get them all at once or do I need to do subqueries? At the least what I would like to be able to do is get the "products" and "faq_categories" with the same query. Looking for help, not sure what to do. Thanks! Steve Tag: DataColumn.Expression questions Tag: 73668
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 - Data Access Peroperties' permissions grayed out I've tried to connect to SQL Server via VS.NET -- and I'm the dbo -- but the permissions area of the Data Access Properties area is grayed out. It only lets me view the objects, not edit/create in Server Browser. Any help is appreciated. Thanks. Tag: DataColumn.Expression questions Tag: 73663
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 - adding data,time and computername to a dataset Hello.. I have a problem in a c# application. I have a dataset that have a table cald tblcounter in this table I have 2 columns Computer_name and datetime. In the computer_name I want to store the clientnamn and in datetime I want to store the date and time the clientnamn was enter in the table This is the C# code I am using. DataRow anyRow = tblcounter.NewRow(); anyRow["processor"] = perf_processor_time.NextValue(); anyRow["memory_fri"] = perf_memory_fri.NextValue(); // the code to add clientnamn and date,time tblcounter.Rows.Add(anyRow); --------------- lennie Tag: DataColumn.Expression questions Tag: 73662
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 - ORA-01002 - fetch out of sequence HELP ME please :) Hello people, I have one problem with Oracle 7 and OracleClient Provider. I have a server with Win 2k and Client of Oracle 9i. My database is in a machine with Oracle 7. In the begininnig the database was in Oracle 9i. and my web application works fine. After I'd put the application in Oracle 7. But a problem became. Every query that I try to execute the error is showed: ORA-01002 - fetch out of sequence Is anyone knows what happened? Thanks a lot. Steven Alexander Tag: DataColumn.Expression questions Tag: 73661
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 - Datagrid problem? Hi! A stored procedure results records via an SqlAdapter to a dataset. I defined a dataview to that dataset for a datagrid. Some column in the grid are hided. The grid and the columns are readonly. And I have a textbox binded to the same dataview. There is a method clear the dataset, then to connect the server, fill the dataset and close the connection. I call this method in the form Load eventhandler. Running the app, I can see the records in the grid and the corresponding field in the textbox and moving in the grid by clicking on rows or by pressing keys is fine until I choose to refresh the dateset via the method mentioned earlier. Then clicking or pressing keys doesn't affect to the textbox value for a small undetermined time (20 - 50 clicks), then it works fine. While it is not working the black triangle stands on that row header, which was reached last time. What can I do? I need the textbox value for other computing. Tag: DataColumn.Expression questions Tag: 73655
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 - datagrid-update I have a datagrid with two columns-name,id and both are editable. My requirement is that I want my second column(id) as a non updatable column.Though I can change the values of column by editing it,upon saying update,the second shouldn't be updated. Do we have to set any property or do it programatically? If so,how? Tag: DataColumn.Expression questions Tag: 73649
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 - Losing strong typing when using DataRow.GetChildRows() This is just a general query about Data Binding. I've got a Custom (VS 2003 generated) DataSet with a number of strongly typed Custom DataTables within. I was trying out using DataRelations to save me doing looping compares in my code but I found that (obviouse in retrospect) DataRow.GetChildRows() returns DataRow[] which means i lose the strong typing of my rows (which i *really* dont want to do). Anyone come across this? Anyone any ideas about working around it? Any future plans for the VS 2003 auto- generated classes to provide helper functions, convertion operators or custom dataset/row contructors that take DataSet/Row as parameters. Thanks in advance Jan Bannister Tag: DataColumn.Expression questions Tag: 73644
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 - SqlDataAdapter.Update doesn't update Hi, In ASP.NET, i've got a web forms app, which does its data operations through a middleware DataManager dll. In one operation, the web form creates a types dataset from a stored schema, adds a DataRow to the single DataTable object and passes this to the dll for upload. ---begin webform function--- { ForumData fData = new ForumData(); PeopleDataSet pds = new PeopleDataSet(); DataTable dt = pds.Tables["People"]; DataRow dr = dt.NewRow(); dr["PeopleID"] = Convert.ToInt32(this.txtPeopleID.Text); dr["Name"] = this.txtName.Text; dr["Email"] = this.txtEmail.Text; dr["Password"] = this.txtPassword.Text; dr["Sig"] = this.txtSig.Text; dr["ShowDetail"] = Convert.ToBoolean(this.txtShowDetail.Text); dr["Photo"] = Convert.ToBoolean(this.txtPhoto.Text); dr["PicApprove"]= Convert.ToBoolean(this.txtPicApprove.Text); dr["MemberApprove"] = Convert.ToBoolean(this.txtMemberApprove.Text); dr["PlainText"] = Convert.ToBoolean(this.txtPlainText.Text); dr["DOB"] = Convert.ToDateTime(this.txtDOB.Text); dr["LastHere"] = Convert.ToDateTime(this.txtLastHere.Text); dr["SignedUp"] = Convert.ToDateTime(this.txtSignedUp.Text); dr["CountPosts"] = Convert.ToInt32(this.txtCountPosts.Text); dr["Title"] = this.txtTitle.Text; dr["AvatarID"] = Convert.ToInt32(this.txtAvatarID.Text); pds.Tables["People"].Rows.Add(dr); bool testval = fData.AlterPersonDetails(pds); //pds.WriteXml("c:\\pdsdataset.xml"); if (testval) { btnChange.Text = "Success"; } else { btnChange.Text = "Failed"; } } -- end webform function ---- That gets passed to the Public method, AlterPersonDetails, which is, naturally, just a passthrough to a private function --- begin Public Method --- public bool AlterPersonDetails(DataSet dsChangedPerson) { bool nValue = false; try { nValue = ChangePersonDetails(dsChangedPerson); } catch { nValue = false; } return nValue; } --- end Public Method --- Now, you'll note that i've taken the precaution of writing the DataSet XML to a file in order to check that it does indeed change. It does. Here's the problem. When mAdapter.Update is called, it doesn't appear to do anything at all. --- begin private function --- private bool ChangePersonDetails(DataSet dsChangedPerson) { bool returnval; SqlConnection mCon = MakeConn(); DataSet dsPeople = new XPeopleDataset(); mCon.Open(); SqlDataAdapter mAdapter = new SqlDataAdapter("SELECT * FROM People", mCon); SqlCommandBuilder mComm = new SqlCommandBuilder(mAdapter); mAdapter.Fill(dsPeople, "People"); dsPeople.Merge(dsChangedPerson.Tables["People"]); dsPeople.AcceptChanges(); dsPeople.WriteXml("C:\\xmlversion.xml"); int g = mAdapter.Update(dsPeople, "People"); mCon.Close(); returnval = true; return returnval; } --- end private function --- So, there's my problem. No exceptions, no problems and no changes to the database! If anyone can help, I'd really appreciate it, -- Rich Tag: DataColumn.Expression questions Tag: 73641
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 - datagrid expression-urgent My select query is a s follows select qty from sales; My datagrid as two template columns with textboxex in Item template.I want to use second template column as a compute column in my datagrid which depends on column 'qty' values of my select statement compute column's value should be as follows if( qty > 10) qty+10 else qty-10 How can give my 'DataBinder.eval(containder.dataitem))' expression to my textbox in html? How can I acheive this? How complex evaluation expressions can be given for datagrid columns either at design time or programatically? plzzz help me out thanks in advance, vijaya Tag: DataColumn.Expression questions Tag: 73640
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 - datagrid expression-urgent My select query is a s follows select qty from sales; My datagrid as two template columns with textboxex in Item template.I want to use second template column as a compute column in my datagrid which depends on column 'qty' values of my select statement compute column's value should be as follows if( qty > 10) qty+10 else qty-10 How can give my 'DataBinder.eval(containder.dataitem))' expression to my textbox in html? How can I acheive this? How complex evaluation expressions can be given for datagrid columns either at design time or programatically? plzzz help me out thanks in advance, vijaya Tag: DataColumn.Expression questions Tag: 73639
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 - DataSet-Generator/Typed Dataset: created class always "Dataset1" Hello, when i create a typed dataset from a given xsd-definition, the ms-dataset-generator always names the dataset-class "Dataset1". Of course it's possible, to rename the class in the source-code. But this modification get lost after every change in the schema. The source-code will be generated new in this case. Any idea, where i can find the right property, to set the classname before the source-code is generated? I use the MS-.NET-IDE and C#. Regards Daniel Tag: DataColumn.Expression questions Tag: 73634
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 - opening en closing Connection takes too much time!!! Hi, When I was looking for the reason my application was runnong so slow I suddenly noticed that it was the opening and closing of the connection that took almost all the time. Like in most of the samples I found I opened the connection everytime I needed it, and closed it after my action. But closing and opening everytime seemed to take very much time, so I opened my connection at the start of the application, and closed it at the end: it runned up to 20 times faster (before 1 action took 3-4 seconds, now I have 5 actions per second). So now my question: what's wrong with opening it one time and closing it at the end? Looking at the smaples I found this seems 'not done'? Does it really take so much resources to leave the connection the whole time open? Isn't the use of a property like this a nicer way to handle the database-connection? Property MyConn() As OleDbConnection Get If Not MyConn2.State = ConnectionState.Open Then MyConn2.Open() End If MyConn = MyConn2 End Get Set(ByVal Value As OleDbConnection) 'nothing? End Set End Property or maybe just before every use a: If Not MyConn.State = ConnectionState.Open Then MyConn.Open() End If Any help, any idea's, any remarks or reflections would be nice. I just thinks the much better performance justifies to leave the connection open. Is there any offical documentation about this? Thanks in advance! Pieter Tag: DataColumn.Expression questions Tag: 73624
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 - Common Connection I'm working on an ADO.NET project. I'd like to declare a Common Variable that can store the Connection String values for a Database. I need this variable to be able to initialise the database connection for all OledbDataAdapters across all Form modules. Thanks! Tag: DataColumn.Expression questions Tag: 73620
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 - Performance of ADO.NET Hello All, We are currently in feasibility study and high level design phase. We need to choose application design according to performance and maintainance. Means our main criteria is Performance and easy Maintainance. We have created one template for just study purpose. 1) Layer That uses Typed DataSet and Stored Procedure In this template, we used Typed Dataset. But somewhere i read that it is maintainable but not giving good performance. Our structure is : Presentation Layer > BAL > DAL > Type Dataset Layer > DL I want information whether this is a good architecture or not. Can anybody suggest me a good architecture with following criteria. Use of Stored Procedure everywhere Performance should be high DAL and BAL Should be there Easy to maintain and programmer friendly :) Give me answers ASAP. Best Regards, and Thank You in Advance. Manish Tag: DataColumn.Expression questions Tag: 73619
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 - IBM OleDb for db2 on Win server 2003 gives error.. I've tried to install IBMs OleDb for db2 on iSeries (Client Access) on both Web Edition and Standard Edition. When I try to instantiate from an asp.net app I get the error message: ********* Non-NULL controlling IUnknown was specified, and either the requested interface was not IUnknown, or the provider does not support COM aggregation. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Data.OleDb.OleDbException: Non-NULL controlling IUnknown was specified, and either the requested interface was not IUnknown, or the provider does not support COM aggregation. ******** Whats this? Any way to make it work? Jon Tag: DataColumn.Expression questions Tag: 73618
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 - Cannot edit Databases on other SQL Servers in Visual Studio Server Explorer I am using Visual Studio .Net 2003 Server Explorer to make any changes to my SQL Server 7 Database that is local to my machine. I also have SQL Server 2000 running on my machine and have recently upgraded the database to SQL Server 2000. Unfortunately I don't seem to be able to make any modifications to the SQL Server 2000 database using Server Explorer. I have also connected to other SQL Server 7 and 2000 databases with the Server Explorer and do not have access to modify any of these databases either. I can make adjustments to the SQL Server 2000 database using Enterprise Manager but I really like the Stored Procedure Editor with the "Design SQL Block" that doesn't exist in Enterprise Manager. Thanks Tag: DataColumn.Expression questions Tag: 73615
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 - What SQL Statement is being passed? Is there a way to show what values are being passed in an SQL Statement? I can display the commandtext of OleDbInsertCommand1 but it displays the "?" is there a way to show the actual values of the insert statement? Thanks Charlie Tag: DataColumn.Expression questions Tag: 73614
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 - OLEDB for FoxPro and SPROCS Is there anyway to call a SPROC using the OLEDB provider for foxPro inside a VB.Net class and then have the ability to reference the column data inside a datareader or datatable? I currently only get a boolean value back when I call a SPROC that executes a simple select statement. HELP PLEASE!! Thanks! Dan Tag: DataColumn.Expression questions Tag: 73613
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 - ADO .net in production environment Hello: I just started looking into ADO .net, and I wonder if it works well in production environment. One of the questions I have is working with multiple tables with ADO .net; that these tables are related. If there are update, insert, delete to the dataset returned from the database. When sending the modified data back to the database, is ADO .net automatically takes care of all the relationship and makes updates in all tables involved? Thanks. Quin Tag: DataColumn.Expression questions Tag: 73611
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 - One bound form, two functions..help please Hi, I'm planing to have a form with 10 bound textboxes to a dataset throgh the currency manager and bindingcontext. What I need to do is use that same form based on the user choice. He/she could first press a button to fill-out all textboxes from dataset and do normal navigation through all records in the dataset, OR he/she could enter a search criteria in the first textbox (txtEmployee ID), press the same button to search and get that specific record only. I don't have any problem with the first case (press the button to get records and navigate), the problem is when the button is pressed for search, how can I search the dataset???? Correct me if i'm wrong, I'm planing to clear the binding property of all textboes and clear thier TEXT property. The question is How to search for that specific record based on the field enter in the textbox(which the choice to search) MTIA, Grawsha Tag: DataColumn.Expression questions Tag: 73605
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 - XSD for existing XML structure. I have an xml file that is currently being used ... I need to make the xsd file for it for intellisense to work in the .net ide. So, when I try to do the xsd file, it keeps giving me an error about the tables being nested and are wrong...so after looking and sifting through google, I'll try here as well :) <store id="WalStore"> <product id="Paint1"> <product id="Paint3"></product> <product id="Paint4"> <product id="Paint5"></product> <product id="Paint6"></product> </product> <product id="Paint7"></product> <product id="Paint8"> <product id="Paint9"></product> <product id="Paint10"> <product id="Paint11"> </product> </product> </product> <product id="Paint2"> <product id="Paint12"></product> </product> </store> So, how can I create the XSD for the above xml? Once I can do that, my problem *should* be solved for my application. Thanks a bunch! Mythran the Pro-g(r)am(m)er Tag: DataColumn.Expression questions Tag: 73602
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 - Expression Column doesn't refresh Hi, I have a problem. I have no any clue about this. Please help me to figure it out. I have a Customers table and Orders table. There is a relation,named "Customer2Orders", between Customers (parent table) and Orders (child table) on CustomerID. One Customer may have multiple Orders. I have an expression column 'Total' in Customers table. It is computed based on the child table's column InvoiceAmount, i.e. Total = Sum(Child(Customer2Orders).InvoiceAmount). If I add a child record, Total is computed automatically. But if I delete a child record, Total is not reflected. It still keeps the old value which is wrong. Thanks in advance! Fei Tag: DataColumn.Expression questions Tag: 73598
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 - need XML help with nested tables Hi- I need to develop an FAQ section for our website. We would like to break up the FAQ by products, then categories with each category having n question/answer pairs. I would like to pass parameters in the querystring based on what the product/category the user selected, then populate a datagrid with the correct set of question/answer I am pretty new to XML, but basically I made something like this: <products> <product> <name>prod1</name> <partNum>prod1</partNum> <categories> <category> <name>basic category</name> <faqs> <faq> <question>This is a sample question</question> <answer>this is the answer</answer> </faq> </faqs> </category> </categories> </product> <product> <name>prod2</name> <partNum>prod2</partNum> <categories> <category> <name>basic something or something category</name> <faqs> <faq> <question>This is another question</question> <answer>and this is another answer</answer> </faq> </faqs> </category> </categories> </product> </products> So, then I use a DataSet and the ReadXML() method, this result in 5 tables. I was hoping that it would somehow be nested for me, but the way it is right now I can't see an easy way to use it the way I want. the first table lists the products(good) the second table I can't really tell what is in there third tables has all the categories, so on and so on. What is confusing is... what is the point of structuring data hierarchically in XML file if you can't maintain it? I'm sure you can, but how? Is what I'm doing not common? Someone please shed a little light on this for me, I would appreciate it!! Thanks, Steve Tag: DataColumn.Expression questions Tag: 73597
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 - Adding a record using C# This is a multi-part message in MIME format. ------=_NextPart_000_0028_01C3BA8B.EDE71230 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Can someone tell me what is wrong with this code? I am simply trying to = add a record to a database. The error message is as follows: An unhandled exception of type 'System.InvalidOperationException' = occurred in system.data.dll Additional information: Update unable to find TableMapping['Table'] or = DataTable 'Table'. ************************************************************** DataSet ds =3D new DataSet(); ds.Tables.Add("FundData"); // Create Access objects:=20 System.Data.OleDb.OleDbCommand cmd1 =3D new = System.Data.OleDb.OleDbCommand("SELECT * FROM FundData", dbConn); System.Data.OleDb.OleDbDataAdapter AdpFunds =3D new = System.Data.OleDb.OleDbDataAdapter(cmd1); AdpFunds.Fill(ds, "FundData"); DataRow dr =3D ds.Tables["FundData"].NewRow(); dr["Symbol"] =3D sym; ds.Tables["FundData"].Rows.Add(dr); ds.AcceptChanges(); AdpFunds.Update(ds); ------=_NextPart_000_0028_01C3BA8B.EDE71230 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=3DContent-Type content=3D"text/html; = charset=3Diso-8859-1"> <META content=3D"MSHTML 6.00.2800.1276" name=3DGENERATOR> <STYLE></STYLE> </HEAD> <BODY> <DIV> Can someone tell me what is wrong with this = code?  I am=20 simply trying to add a record to a database.  The error message is = as=20 follows: An unhandled exception of type=20 'System.InvalidOperationException' occurred in = system.data.dll Additional information: Update unable to find=20 TableMapping['Table'] or DataTable 'Table'. <FONT=20 face=3DArial>************************************************************= ** DataSet ds =3D new=20 DataSet(); ds.Tables.Add("FundData"); // Create Access objects: = <FONT=20 size=3D2> System.Data.OleDb.OleDbCommand cmd1 =3D new = System.Data.OleDb.OleDbCommand("SELECT * FROM=20 FundData", dbConn); System.Data.OleDb.OleDbDataAdapter AdpFunds =3D new = System.Data.OleDb.OleDbDataAdapter(cmd1); AdpFunds.Fill(ds, "FundData"); DataRow dr =3D ds.Tables["FundData"].NewRow(); dr["Symbol"] =3D sym; ds.Tables["FundData"].Rows.Add(dr); ds.AcceptChanges(); AdpFunds.Update(ds);</DIV></BODY></HTML> ------=_NextPart_000_0028_01C3BA8B.EDE71230-- Tag: DataColumn.Expression questions Tag: 73595
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 - Error in stored procedure Hi, I just wanted to ask what is wrong with this stored procedure. i keep getting the following error message: ADO error: The column prefix 'dbo' does not match with a table name or alias name used in the query. ALTER PROCEDURE dbo.SPSelEquipBooked2 (@Arrival datetime, @Departure datetime) AS SELECT dbo.Equip_Inv_No FROM dbo.Equipment_Inv WHERE dbo.equipment_Inv.Equipment_Inv_No Not In( SELECT dbo.Equipment_Inv.Equip_Inv_No FROM dbo.Equipment_Booking INNER JOIN dbo.Equipment_Inv ON dbo.Equipment_Booking.Equip_Inv_No = dbo.Equipment_Inv.Equip_Inv_No INNER JOIN dbo.Caravan_booking ON dbo.Equipment_Booking.BookingNo = dbo.Caravan_booking.BookingNo AND dbo.Equipment_Booking.Caravan_Inv_No = dbo.Caravan_booking.Caravan_Inv_No INNER JOIN dbo.Booking_Details ON dbo.Caravan_booking.BookingNo = dbo.Booking_Details.BookingNo WHERE (dbo.Booking_Details.Dt_of_departure >= @Arrival) AND (dbo.Booking_Details.Dt_of_arrival <= @Departure)) thx in advance Tag: DataColumn.Expression questions Tag: 73591
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 - Question about nested transaction in ADO.NET I am using SQL Server 2000 as data storage I have a transaction which has the following structure connection.begintran Process A Process B Process C connection.commit rollback when failed In each process(A, B, C), there will also be BeginTran, Commit & Rollback inside it. I have such structure because process A, B, C are methods provided by different object. I have found that when I failed in process B, A will not be rollback... So how can I implement a nested transaction? Thanks Tag: DataColumn.Expression questions Tag: 73583
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 - read an output parameter from a stored procedure by its name? hi. I cannot retrieve an output parameter from a stored procedure by name. Is this correct? Works not: [ sParamValue = mycmd.Parameters["@ID"].Value.ToString(); ] Works fine: [ sParamValue = mycmd.Parameters[0].Value.ToString(); ] TIA /OF Tag: DataColumn.Expression questions Tag: 73578
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 - Datagrid - upgrade / save new rows I have an ADO.NET connection to an Access 2000 DB with 1 table. I have a Data Grid that shows me all records when I open the Data Grid. In the program it shall be possible to add rows to the table directly in the grid, by adding rows. Have tried to code this, but the result is only an empty new row. The information in the row is lost. Can anybody help? I have OleDgDataAdapter called 'da', OleDbConnection called 'cn', a dataset called 'ds1'. NSR Tag: DataColumn.Expression questions Tag: 73572
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 - Reading text file using ADO.net This is a multi-part message in MIME format. ------=_NextPart_000_01AA_01C3BAA0.55E26560 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hope somebody can help... I'm trying to load up a text file using ADO.net, as follows: Dim TextConnectionString As String TextConnectionString =3D "Provider=3DMicrosoft.Jet.OLEDB.4.0;" & _ "Data Source=3D" & FilePath & ";" & _ "Extended Properties=3D""Text;HDR=3DNO;FORMAT=3DDelimited""" Dim TextConn As New = System.Data.OleDb.OleDbConnection(TextConnectionString) TextConn.Open() Dim da As New System.Data.OleDb.OleDbDataAdapter("Select * from " & = filename, TextConn) Dim ds As DataSet =3D New DataSet("CSVFiles") da.Fill(ds, filename) When I run this, it fails at the "fill" statement with the error = "Database or object is read only". The file in question can definitely be read and written (it's a short = CSV file). What have I done wrong??? Many thanks in advance. Simon ------=_NextPart_000_01AA_01C3BAA0.55E26560 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=3DContent-Type content=3D"text/html; = charset=3Diso-8859-1"> <META content=3D"MSHTML 6.00.2800.1276" name=3DGENERATOR> <STYLE></STYLE> </HEAD> <BODY> <DIV>Hope somebody can help...</DIV> <DIV> I'm trying=20 to load up a text file using ADO.net, as follows: <FONT=20 size=3D2>Dim TextConnectionString As=20 String TextConnectionString =3D "Provider=3DMicrosoft.Jet.OLEDB.4.0;" = &=20 _ "Data Source=3D" & FilePath & ";" & _ "Extended=20 Properties=3D""Text;HDR=3DNO;FORMAT=3DDelimited""" Dim TextConn As = New=20 System.Data.OleDb.OleDbConnection(TextConnectionString) TextConn.Open(= ) Dim=20 da As New System.Data.OleDb.OleDbDataAdapter("Select * from " & = filename,=20 TextConn) Dim ds As DataSet =3D New = DataSet("CSVFiles") da.Fill(ds,=20 filename) When I run this, it fails at the "fill" = statement=20 with the error  "Database or object is read only". The = file in=20 question can definitely be read and written (it's a short=20 CSV file).     What have I done = wrong??? Many=20 thanks in=20 advance. Simon </DIV></BO= DY></HTML> ------=_NextPart_000_01AA_01C3BAA0.55E26560-- Tag: DataColumn.Expression questions Tag: 73570
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 - sqlCommand.ExecuteScalar return value 'undefined value' How can that be? Isn't it supposed to return dbnull if there is nothing in the select? Ronen Tag: DataColumn.Expression questions Tag: 73564
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 - Queries Hi, I am new to ADO and still have a lot to learn from you. In Access, I used to have make queries (sometimes based on other queries) and display them in a form. In ADO.NET, there is a dataset. But I could not figure out how to do this. Is there any examples I can get? Tag: DataColumn.Expression questions Tag: 73563
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 - Error whne dragging table to dataset Hi When I drag a table onto a dataset from the server explorer I get a Data Adapter Configuration Error...'Error in SELECT clause: expression near "".....'. How can I fix this? I am using FoxPro tables. Thanks Regards Tag: DataColumn.Expression questions Tag: 73562
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 - Help with DataTable update (BeginLoadData method) I have an ASP.NET/VB app that updates values in a DataTable over the course of about 3 different pages. On the way out of the first of these pages, I explicitly build the DataTable from values in a DataGrid, and set the PrimaryKey of the DataTable to be the first cell in the grid (which is a UserID value). I then store the DataTable in a session object, from which it is retrieved for subsequent pages. All this seems to be working fine. On the second page, I retrieve the DataTable from the session object, apply a filter to it, and display the filtered data in a DataGrid. In this grid, the user can change the data, specifically assigning an employee to a different supervisor. The Grid is populated with the current employee/supervisor assignment in the database, and then any necessary changes are made by the user. This, too, seems to be working fine. The problem I'm having is that on the update command of the Grid, which is where I'm updating the DataTable (the thought being that I would just do an "in-place" update of the DataTable and then rebind the grid). I am able to trap the new assignment values (which are set in a listbox within the grid) and can trap the employee ID value from the grid (which is my primary key), but whenever I call the LoadDataRow method, rather than updating the row based on the primary key, a new row insert is *attempted*. I say attempted because I get an error on the EndLoadData method, which I believe is due to not passing in values for all the columns. I was hoping to be able to just pass in the key value and the values of the columns that had changed, but apparently that is not sufficient. Which is the first question - when attempting a LoadDataRow call, do I need to pass in valid values for *all* of the columns in the datatable (except, of course, those for which there are default values, of which I have none in this instance). You'll see in my example code that I'm just passing in the first, eighth and ninth columns, which I suspect is the problem. However, the *real* question is why isn't the LoadDataRow method finding the pre-existence of the key value in the table? I've checked and the value returned by my code is exactly the same as the one in the table, length is the same, etc. I set the primary key when I first build the table on the previous page, but I thought perhaps that attribute somehow gets lots when I set the DataTable to a session object so, as you will see in the example, I explicitly set the primary key again on this page, which seems to work, but the code still inserts a new row (or attempts to). Here is the relevant code from the page in question: Dim DDL As DropDownList = CType(e.Item.Cells(2).Controls(1), DropDownList) Dim NewID As Integer = DDL.SelectedIndex Dim SupervisorID As String = DDL.Items(NewID).Value Dim SupervisorName As String = DDL.Items(NewID).Text Dim NewRow(9) As Object Dim Key As TextBox = e.Item.Cells(1).Controls(0) Dim RowID As String = Key.Text Dim dsTechnicianList As DataTable dsTechnicianList = CType(HttpContext.Current.Session("ILApplicators"), System.Data.DataTable) Dim dcFirst As DataColumn = dsTechnicianList.Columns(0) Dim dcPrimary(1) As DataColumn dcPrimary(0) = dcFirst dsTechnicianList.PrimaryKey = dcPrimary NewRow(0) = RowID NewRow(7) = SupervisorName NewRow(8) = SupervisorID Dim myRow As DataRow dsTechnicianList.BeginLoadData() myRow = dsTechnicianList.LoadDataRow(NewRow, True) dsTechnicianList.EndLoadData() Any help or ideas would be GREATLY appreciated! TIA, Mike Tag: DataColumn.Expression questions Tag: 73561
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 - Rollback Transaction Timing Out Framework 1.0 SQL Server 2000 After aborting a long (around 10 minutes) and with numerous updates, the Rollback function will raise an exception giving the message: System.Data.SqlClient.SqlException: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. -- at System.Data.SqlClient.SqlTransaction.Rollback() If the transaction is not aborted, ie the Commit function is called, a timeout does not occur. In extracts from source below the timeout is set to 0 (for ever). Does anyone have experience of the Rollback timing out? ...... addCon = new System.Data.SqlClient.SqlConnection(); ...... System.Data.SqlClient.SqlCommand addCom = new System.Data.SqlClient.SqlCommand(); Try { ..... addCom.Connection = addCon; addCom.CommandTimeout = 0; //go on for ever addCon.Open(); //Start Transaction addCom.Transaction = addCon.BeginTransaction(); transactionStarted = true; ....... catch(Exception e) { ImportController.errorLevel = errorLevelMajorError; Audit("ERROR: Update PDS " + e.ToString()); if (transactionStarted) { errorLevelTransactionRolledBack = errorLevelTransactionRolledBack; addCom.Transaction.Rollback(); <<--- Times out here } addCon.Close(); addCom.Dispose(); } Thanks in advance Tag: DataColumn.Expression questions Tag: 73559
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 - Append 1 Datatable to another (same schema)?? I have several datatables that are of the identical schema, each holding different data. There are times when it would be nice to combine the data from two datatables into one datatable. Would prefer not having to do this through looping. What would be the best way to do this? Tag: DataColumn.Expression questions Tag: 73556
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 - Refilling table Hi I have several tables in a dataset. How can I reread the data from underlying database in only one of the tables? Thanks Regards Tag: DataColumn.Expression questions Tag: 73555
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 - User Defined Sql Function and ADO.Net Hi all, Does anyone know the syntax for returning a value from a user defined function in Sql Server using VB.Net. Each time I do it I get: invalid object name We have a function which takes one parameter and returns a table. I can find little or no documents directly addressing this subject. Thanks in advance, Bill Tag: DataColumn.Expression questions Tag: 73554
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 - Multiple Access Databases I want to redo my Forms in VB.NET. Now when I go and test my Forms to make sure they work I want to set up a second ACCESS file as a test database. When everything works and I want to switch over to my Production database how would I do that? Would I have to go into all my VB forms and redo my ADO links or is there an easier way? Tag: DataColumn.Expression questions Tag: 73551
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 - OleDB returning DBNull for certain cells Hi, I'm using OleDBConnection to read data from Excel. I'm able to read everything except when a cell has numeric value and the column has alphanumeric data. I get DBNull when it encounters a numeric value. I'm sure many people have seen this. Does anyone know how to address this issue? Thanks, Paul Tag: DataColumn.Expression questions Tag: 73550
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 - Can Sql Server 7 be used with ADO.Net? Does ADO.Net work with SQL Server 7 or is it only compatible with SQL Server 2000? Thanks in advance Chris Pearce Tag: DataColumn.Expression questions Tag: 73546

I'm trying to utilize the DataColumn.Expression property and am stuck on 2
issues.

1) I am running into rounding problems on decimal fields. If I have
col3.Expression = col1 / col2, col3 seems to truncate the value instead of
rounding (12.888 showing as 12.88 instead of 12.89). Is there a way to
force the field to round?

2) I have a calculation col4.Expression = ((col5 - col6) / col6) * 100 which
is returning an error message "Attempting to divide by 0". Col6 is a
calculated field that has a valid value. I tried changing the Expression to
Iif(col6=0,0,((col5 - col6) / col6) * 100) but I'm still getting the divide
by 0 error. Can I not use a calculated field to populated another
calculated field?

Thanks

Top

Re: DataColumn.Expression questions by Miha

Miha
Fri Dec 05 15:47:55 CST 2003

Hi Jennifer,

I would strongly recommend against expressions.
Rather, calculate it yourself and put data in.
In 2) I guess the column is being calculated before col6.

--
Miha Markic - RightHand .NET consulting & development
miha at rthand com

"Jennifer Johnson" <jajohnson@epicor.com> wrote in message
news:e2l3Gj3uDHA.1888@TK2MSFTNGP10.phx.gbl...
> I'm trying to utilize the DataColumn.Expression property and am stuck on 2
> issues.
>
> 1) I am running into rounding problems on decimal fields. If I have
> col3.Expression = col1 / col2, col3 seems to truncate the value instead of
> rounding (12.888 showing as 12.88 instead of 12.89). Is there a way to
> force the field to round?
>
> 2) I have a calculation col4.Expression = ((col5 - col6) / col6) * 100
which
> is returning an error message "Attempting to divide by 0". Col6 is a
> calculated field that has a valid value. I tried changing the Expression
to
> Iif(col6=0,0,((col5 - col6) / col6) * 100) but I'm still getting the
divide
> by 0 error. Can I not use a calculated field to populated another
> calculated field?
>
> Thanks
>
>

Top