CODEWITHSUNDEEP
c#databasevisual-studio-2012dataset
Syed Farjad Zia Zaidi
Syed Farjad Zia Zaidi

Reputation: 3360

Can't get updating of dataset working

I have got a couple of questions. I am making gym management system to submit in my university. I implemented a service based database by reading the tutorials at www.homeandlearn.co.uk. The problem is I can not update it 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Gym_Management_System
{
   class GMSDConnectionClass
   {
      public string sql_string;
      public string strCon;

      public string Sql
      {
          set { sql_string = value; }
      }

      public string connection_string
      {

          set { strCon = value; }

      }

      public System.Data.DataSet GetConnection
      {

          get { return MyDataSet(); }

      }

      public System.Data.DataSet MyDataSet()
      {
          System.Data.SqlClient.SqlConnection con = new
                                       System.Data.SqlClient.SqlConnection(strCon);
          con.Open();
          System.Data.SqlClient.SqlDataAdapter da_1 = new
                              System.Data.SqlClient.SqlDataAdapter(sql_string, con);
          System.Data.DataSet dat_set = new System.Data.DataSet();
          da_1.Fill(dat_set, "Table_data_1");
          con.Close();
          return dat_set;
      } 

      public void UpdateDatabase(System.Data.DataSet ds)
      {
          System.Data.SqlClient.SqlCommandBuilder cb = new
            System.Data.SqlClient.SqlCommandBuilder(da_1);

          cb.DataAdapter.Update(ds.Tables[0]);
      }
   }
}

The problem is that I can not access da_1 in UpdateDatabase() method.

What's wrong there? I have tried couple of things but I couldn't get it. It may be a simple problem but I am totally new to database and this stuff.

Note: I have to submit this project on 23rd January 2014.

Upvotes: 1

Views: 134

Answers (1)

Simon Whitehead
Simon Whitehead

Reputation: 65049

Variables cannot be accessed outside of their declaring scope. There are various scoping rules.. the one you're most concerned with here is method-scope. This might help explain:

 public System.Data.DataSet MyDataSet()
 {
      // da_1 is delcared in this method.. it is only available here
      ...
      System.Data.SqlClient.SqlDataAdapter da_1 = new
                          System.Data.SqlClient.SqlDataAdapter(sql_string, con);
      ...
 } 

 public void UpdateDatabase(System.Data.DataSet ds)
 {
      // not available here
 }

In order to access it across methods within a class.. you must declare it at class level:

class GMSDConnectionClass
{
    System.Data.SqlClient.SqlDataAdapter da_1;

Then you can assign it like this in your other method:

da_1 = new System.Data.SqlClient.SqlDataAdapter(sql_string, con);

Upvotes: 1

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