Usman ur Rehman Ahmed's blog

I encountered this exception today while trying to read a data set from MySql database from C# .NET using MySql connector and enterprise library. Complete stack trace of this exception is below,

{MySql.Data.MySqlClient.MySqlException: The user specified as a definer ('root'@'%') does not exist

   at MySql.Data.MySqlClient.MySqlStream.ReadPacket()

   at MySql.Data.MySqlClient.NativeDriver.GetResult(Int32& affectedRow, Int32& insertedId)

   at MySql.Data.MySqlClient.Driver.GetResult(Int32 statementId, Int32& affectedRows, Int32& insertedId)

   at MySql.Data.MySqlClient.Driver.NextResult(Int32 statementId)

   at MySql.Data.MySqlClient.MySqlDataReader.NextResult()

   at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior)

   at MySql.Data.MySqlClient.MySqlCommand.ExecuteDbDataReader(CommandBehavior behavior)

   at System.Data.Common.DbCommand.System.Data.IDbCommand.ExecuteReader(CommandBehavior behavior)

   at System.Data.Common.DbDataAdapter.FillInternal(DataSet dataset, DataTable[] datatables, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior)

   at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior)

   at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet)

   at Microsoft.Practices.EnterpriseLibrary.Data.Database.DoLoadDataSet(IDbCommand command, DataSet dataSet, String[] tableNames)

   at Microsoft.Practices.EnterpriseLibrary.Data.Database.LoadDataSet(DbCommand command, DataSet dataSet, String[] tableNames)

   at Microsoft.Practices.EnterpriseLibrary.Data.Database.LoadDataSet(DbCommand command, DataSet dataSet, String tableName)

   at Microsoft.Practices.EnterpriseLibrary.Data.Database.ExecuteDataSet(DbCommand command)

 This happens when you try to make connection with MySql database from within .NET and is a privileges issues. For resolution, please follow these steps,

1- Run > Command Prompt

                Move to C:\Program Files\MySql\bin folder. Path for me appears as following,

       C:\Program Files\MySQL\MySQL Server 5.5\bin> 

2- Log into My Sql by exeucting the following command,

       mysql -u root -p

                You will be prompted for password.

       Enter password:

                On successfull password input you will log into mySql console,

                mysql> _

3- Grant All Privileges

                Execute following command under my sql console,

       grant all privileges on *.* to `root`@`%` identified by 'password';

                Upon successfull completion of command you will recieve confirmation simialr to this,

                Query OK, 0 rows affected (0.05 sec)

Note: Pay special heed to position of apostrophe vs. commas. Usernameis enclosed within apostrophy (`) where as password within commas (').

4- Flush Privileges

                Execute following command to ensure the privileges take affect,

       flush privileges;

                which will result in notification similar to this,

                Query OK, 0 rows affected (0.11 sec)

                You are done. Switch back to Visual Studio to test your settings are properly taking affect. To exit mysql console type exit and press enter. Above steps are summarized in figure below,

Background Context

I am using EVDO broadband wireless Usb stick launched by Pakistan Telecommunication Limited (a 3.1 Mbps device). It is based on "CDMA2000" 3G wireless standard. It works well for me since I am at a rather lesser IT aware populated location. I came across an issue today while trying to capture network traffic on top of EVDO stick. I couldn't find much on this topic so I decided to write a post on this.

The Problem

I was able to get the network interface against EVDO using System.Net.NetworkInformation namespace,

foreach (NetworkInterface nic in NetworkInterface.GetAllNetworkInterfaces()) { ... }

 as following,

                "WAN (PPP/SLIP) Interface"

OS: Windows XP (x86)

with following,

WinPCap: 4.1.1

WireShark: Version 1.2.8 (SVN Rev 32676)

SharpPCap: SharpPcap-3.5.0

Solution

Since WAN (PPP/SLIP) interface is no exception I was forced to think that the issue is not due to usb modem but rather with WinPCap. I goggled it a bit and identified that PPP capturing is possible on Windows XP (x86) with WinPCap last stable release version (at the time of this writing) 3.1 which can be downloaded from,

                http://www.winpcap.org/archive/3.1-WinPcap.exe

-          I uninstalled 4.1.1 and reverted back to 3.1 and on the go, both network interfaces (Generic dialup adapter & WAN (PPP/SLIP interface) ) were listed relative to EVDO under WireShark and using SharpPCap (since it utilizes WinPCap).

Note: As per initial tests, I was able to capture traffic using Wireshark but while trying to open either of these interfaces using SharpPCap, I was getting an exception at device.Open(),

"Unable to open the adapter (rpcap://\Device\NPF_GenericDialupAdapter). Error opening adapter: The system cannot find the device specified. (20)"

OR

Unable to open the adapter (rpcap://\Device\NPF_{F9409E20-55C1-43AD-992A-10929B.....}). Error opening adapter: The system cannot find the device specified. (20)

However since this post is primarily relative to listing of interfaces, the resolution was found. I will speak more on the issue of communication with EVDO device using SharpPCap in another blog post.

References

More details on the topic of PPP capturing can be found at,

                http://wiki.wireshark.org/CaptureSetup/PPP

                http://www.winpcap.org/misc/faq.htm#Q-5

I actually was explaining a fresh into development guy how row command events of data elements work within ASP .NET. Once he was able to complete a test page, I came across this check,

    protected void grdGlassThickness_RowCommand(object sender, GridViewCommandEventArgs e)
    {
        if (e.CommandName.ToString() == “Delete”) {

        }
    }

To explain him that there are commands which will always remain as it is throughout the application and in most of the applications; I encouraged him to use enumerations for comparison purposes rather than sticking with string. For other young fellows, this post will explain this very basic concept.

Considering the declaration of LinkButton within grid control item template in .ascx control as following,

    <asp:LinkButton ID="lnkBtnDelete" runat="server" Text="Delete"  CssClass="GridColumn"
        CommandArgument='<%# Eval("GlassId") %>' CommandName="<%= CommandTypes.Delete.ToString() %>">
    </asp:LinkButton>

For comparison purposes, An enumeration is declared as following,

    public enum CommandTypes
    {
        Delete,
        Edit,
        Insert
    }

And the comparison finally takes place as following,

    protected void grdCustomers_RowCommand(object sender, GridViewCommandEventArgs e)
    {
        try
        {
            if (e.CommandName.ToString() == CommandTypes.Delete.ToString()) {
                  
            }
        }
    }