Concurrency Violation Exception

Dec 15 2009 11:02 PM
Hi i am writing displaying a table using DataGridView. My Table is dynamic in the sense it is created only after the application is running so there is no chance i can know about the no of columns available. However, i am having useridauto, which will always be the primary key and it is also autoincrement. So, i need to write my own insertcommand and updatecommand. My code is as follows:

************************************************
 'this is used to dynamically create a insert command according to the table
        Dim ins As New OleDbCommand

        'insert command
        query = "INSERT INTO T_" & frmHome.strSelectedSet & "( "
        j = Nothing

        For Each j In gridviewAnswerData.Columns
            'leave the first column which is useridauto
            If Not j.Name = gridviewAnswerData.Columns(0).Name Then
                query += j.Name & ","
            End If
        Next


        query = query.Remove(query.Length - 1, 1)

        query += ") VALUES( "

        For Each j In gridviewAnswerData.Columns
            'leave the first column which is useridauto
            If Not j.Name = gridviewAnswerData.Columns(0).Name Then
                query += "@" & j.Name & ","
            End If

        Next

        query = query.Remove(query.Length - 1, 1)

        query += ")"

        MessageBox.Show(query)



        'assigning the insert command
        ins.CommandText = query
        ins.Connection = New OleDbConnection(IshaData.My.Settings.ishaConnectionString)
        daSet.InsertCommand = ins

        For Each j In gridviewAnswerData.Columns
            'leave the first column which is useridauto
            If Not j.Name = gridviewAnswerData.Columns(0).Name Then
                daSet.InsertCommand.Parameters.Add("@" + j.Name, OleDbType.VarChar).SourceColumn = j.Name
            End If


        Next


        'Update command
        query = "UPDATE T_" & frmHome.strSelectedSet & " SET "
        j = Nothing

        For Each j In gridviewAnswerData.Columns
            'leave the first column which is useridauto
            If Not j.Name = gridviewAnswerData.Columns(0).Name Then
                query += j.Name & "=" & "@" & j.Name & ","
            Else
                MessageBox.Show(j.Name)
            End If

        Next

        query = query.Remove(query.Length - 1, 1)

        query += " WHERE Useridauto=@" + gridviewAnswerData.Columns(0).Name



        MessageBox.Show(query)

        MessageBox.Show(gridviewAnswerData.Columns(0).Name)

        'assigning the insert command
        ins.CommandText = query
        ins.Connection = New OleDbConnection(IshaData.My.Settings.ishaConnectionString)
        daSet.UpdateCommand = ins

        For Each j In gridviewAnswerData.Columns
            'leave the first column which is useridauto
            If Not j.Name = gridviewAnswerData.Columns(0).Name Then
                daSet.UpdateCommand.Parameters.Add("@" + j.Name, OleDbType.VarChar).SourceColumn = j.Name
            End If

        Next

        daSet.UpdateCommand.Parameters.Add("@" + gridviewAnswerData.Columns(0).Name, OleDbType.Integer).SourceColumn = gridviewAnswerData.Columns(0).Name
        daSet.UpdateCommand.Parameters("@Useridauto").SourceVersion = DataRowVersion.Original
************************************************

My Database is MS ACCESS. My
insert command is working fine, but update command is not working and it is showing concurrency violation when i try to update. Any other details needed ill be happy to give. Please help.
       


Answers (2)