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.NET Forum / .NET Framework / ADO.NET / March 2004Paging, update, concurrency violation..
Dear reader because of a large number of records in a database table I'm using paging. 1 record is being fetch everytime I requery the database (just the record the user requires). When I skip to the next record I check if the row has changes. If it does I generate this updatecommand cmd = New OleDbCommand("UPDATE Customers SET Customers.[Name] = ?, Customers.[Lastname] = ? " & "WHERE Customers.[CustID] = ?", mdbConnection cmd.Parameters.Clear( cmd.Parameters.Add("CustID", OleDbType.Char).Value = CType(dsCustomers.Tables(0).Rows(0).Item("CustID"),Integer) cmd.Parameters.Add("Name", OleDbType.Char).Value = Me.txtTName.Tex cmd.Parameters.Add("Lastname", OleDbType.Char).Value = Me.txtTLastname.Tex daCustomer.UpdateCommand = cm The problem is now that when I update, I get a concurrency violation (???). The strange thing is I'm the only one using this database and I don't get the concurrency violation when I'm using this parameter cmd.Parameters.Add("CustID", OleDbType.Char).Value = 2 What could this be Thx! Hi Maurice, Why do you not put a line between it to debug (I do not know if you use VS.net) > cmd.Parameters.Clear() dim mytest as integer = CType(dsCustomers.Tables(0).Rows(0).Item("CustID"),Integer)) (and if you have not vs.net) messagebox.show(mytest.tostring) > cmd.Parameters.Add("CustID", OleDbType.Char).Value = > cmd.Parameters.Add("Name", OleDbType.Char).Value = Me.txtTName.Text I think than you should know it. I hope this helps? Cor Hi Cor The messagebox shows 0 Why do I get a concurrency violation? I don't get it I constructed the dataset and dataadapter in run-time. Hi Maurice, Show some code from the Select part. It means that that ID is empty, so there it cannot find the row to update. (Or you should have a record with an id 0, which you have already readed (fill) again) Cor Hi Cor, the select statement has 4 different selects, depends on what direction the user wants to go to (paging up or down or first or last record): This is one statement: selCmd.CommandText = "SELECT TOP " & pageSize & " Customers.[CustID],* FROM Customers " & _ "WHERE Customers.[CustID] > ? ORDER BY Customers.[CustID]" selCmd.Parameters.Add("CustID", OleDbType.Integer).Value = CType(lastVisibleCustomer, Integer) I checked the code but the key isn't 0. It has a value. When I enter this value in the code it does update without a concurrency violation. When I refer to the key in the dataset (which has the same value) I do get the concurrency violation. thx.. Hi Maurice, Can you check your columnnames To check that messagebox.show(dsCustomers.tables(0).datacolumn(0).name) messagebox.show(dsCustomers.tables(0).datacolumn(1).name) etc Cor Cor this is the situation (1 cmd = New OleDbCommand("UPDATE Customers SET Customers.[Name] = ?, customers.Lastname] " & "WHERE Customers.[CustID] = " & intCurrentKey & "", mdbConnection cmd.Parameters.Clear( .... (2 cmd = New OleDbCommand("UPDATE Customers SET Customers.[Name] = ?, customers.Lastname] " & "WHERE Customers.[CustID] = ?", mdbConnection cmd.Parameters.Clear( cmd.Parameters.Add("CustID", OleDbType.Integer).Value = intCurrentKe ... Situation 1 works fine, Situation 2 gives a concurrency violation........ Hi Maurice, I never used this with OleDb, however the documentation says that it has to be the same as with the SQL parameter. (Although strange is that that 20 did work) > cmd.Parameters.Clear() > cmd.Parameters.Add("@CustID", OleDbType.Integer).Value = intCurrentKey > .... Can you try that? Cor Hi Cor when I use the @ I get a lot of errors. e.g. This doesn't work for typ DBNull Strange problem, but I will use the first solution which does work. Thank you for the support!! #2) You need a second parameter fir the name added BEFORE the CustId parameter. OleDb parameters must be added in order. Ron Allen > Cor this is the situation: > [quoted text clipped - 12 lines] > > Situation 1 works fine, Situation 2 gives a concurrency violation......... Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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