Problem when running SQL query

foreach (DataRow masterRow in dst.Tables["Menu"].Rows)
{
  MenuItem masterItem = new MenuItem((string)masterRow["Parentitem"]);
  string mp = masterItem.Value;

  SqlParameter parameter = new SqlParameter();
  parameter.ParameterName = "@mp";
  parameter.SqlDbType = SqlDbType.NVarChar;
  parameter.Direction = ParameterDirection.Input;
  parameter.Value = mp;

  string q = "select aspnet_PersonalizationPerUser.hasRights 
              from Menu,aspnet_Users,aspnet_Paths, aspnet_PersonalizationPerUser 
              where  Menu.Parentitem=@mp and Menu.Url = aspnet_Paths.Path 
                     and aspnet_Paths.PathId =aspnet_PersonalizationPerUser.PathId 
                     and aspnet_Users.UserName ='admin' 
                     and aspnet_PersonalizationPerUser.UserId = aspnet_Users.userId ";

   SqlCommand cm = new SqlCommand(q, conn);
   string b = (string)cm.ExecuteScalar();
   if (b == "true")
   {
        Menu1.Items.Add(masterItem);
   }

So when I run the app it says need to declare scalar variable开发者_高级运维 mp .. can u let me know the mistake?

You need to add the parameter to the command.

SqlCommand cm = new SqlCommand(q, conn);
cmd.Parameters.Add(parameter);
string b = (string)cm.ExecuteScalar();

You need to actually add the parameter to the SqlCommand object.

Off the top of my head I think its something like:

cm.Parameters.Add(parameter);

Do this before you call ExecuteScalar

You are just creating a parameter, not adding it to your command. Try adding this before executing the command:

cm.Parameters.Add(parameter);

You have forgot to add the parameter @mp to your command

cm.Parameters.Add(parameter)