CRUD datagridview from/to SQL Server with C# in Winforms

Question

Hi CSharpers, I am trying to crud my datagridview and SQL Server, something is wrong with my code, could anyone check and update my codeblock please. I used the adventureworks SQL database.

I first got an error that there aren't tables in the update, than I changed something in the coding and now I receive an error "The ConnectionString Property has not been Initialized".

I added a datasource directly to the datagridview tasks 'wizard', which generated a  dataset, tableadaptermanager..., after this I drag and dropped the customer details table from the 'Data source explorer' on my datagridview, ran the application and I could see the info.

I added 3 buttons: 

• a button to **update** the datagrid and database after I changed any existing information *or* after I added a row, 

• a button to **delete** selected row(s), 

• and a final button to undo any changes I did(deletion, change of info or insertion of row).

If you could check my queries and coding, it has taken all of my time and skills in this field till now  ... I can't find out what's really missing. I have checked a lot of websites ... but can't figure it out. If you could read my code and adapt it so if works, thank you.

Thanks a lot for making this work for me, much appreciated.

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows.Forms;

using System.Data.SqlClient;

namespace WindowsFormsApplication1

{

    public partial class FormAdventureCustomers : Form

    {

        SqlDataAdapter dar = new SqlDataAdapter();

        SqlConnection con = new SqlConnection();

        DataSet ds = new DataSet();

        public FormAdventureCustomers()

        {

            InitializeComponent();

        }

        private void FormAdventureCustomers_Load(object sender, EventArgs e)

        {

            try

            {

                this.customerTableAdapter.Fill(this.adventureWorks2012DataSet.Customer);

                con.Open();

            }

            catch (Exception error)

            {

                MessageBox.Show("ERROR" + error.Message);

            }

        }

        private void UpdateBtn_Click(object sender, EventArgs e)

        {

            try

            {

                dar.UpdateCommand = new SqlCommand(@"UPDATE Customer SET StoreID WHERE CustomerID=1;", con);

                dar.UpdateCommand.Parameters.Add("@CustomerID", SqlDbType.Int, 4, "CustomerID");

                DataSet ds = new DataSet();

                dar.TableMappings.Add("Customer", customerTableAdapter.ToString());

                dar.Update(this.adventureWorks2012DataSet.Customer);

            }

            catch (Exception error)

            {

                MessageBox.Show("ERROR" + error.Message);

            }

        }

        

        private void DeleteBtn_Click(object sender, EventArgs e)

        {

            try

            {

                dar.DeleteCommand = new SqlCommand(@"DELETE FROM Customer WHERE CustomerID = @CustomerID;", con);

                dar.DeleteCommand.Parameters.Add("@CustomerID", SqlDbType.Int, 4, "CustomerID");

                dar.TableMappings.Add("Customer", customerTableAdapter.ToString());

            }

            catch (Exception error)

            {

                MessageBox.Show("ERROR" + error.Message);

            }

        }

    private void UndoBtn_Click(object sender, EventArgs e)

        {

        }

    }

}