First step open new project and named as in this application like DataGridview_Application.

Create a New Form with one Gridview Control as shown below with the help of arrow and one Close Button as you can see below in the snapshot.

 privatevoid Update_Load(object sender, EventArgs e)
         {
 //Creating Connection with server name,uid,password and database.
        SqlConnection con =  newSqlConnection("server=abc-pc1\\sqlexpress; uid=sa; password=sa; database=Mind");
           //connection is open
              con.Open();
       //Creating object for dataAdapter     
 SqlDataAdapter sda = new SqlDataAdapter("select * from Employee", con);
 //craeting datatable object
            DataTable dt = newDataTable();
            sda.Fill(dt);
 //accessing data in grid
            dataGridView1.DataSource = dt;
  
        } }

Output of the this code look likes as:

//then double click on the close button place a code for closing the application

 this.Close();

Next step is to access rows in the gridview in another form as we have created another form named “New Form” as shown below,for adding another form in the same application you have to Rightclick on the datagridview_Application option on the right side of the application and right click over there then click on add items as shown below and named NewForm.

Next we have to show fields on the event of “cellclick “ option in the gridview ,for that under properties option you will find an option Event under that you will see an option “cellClick” then double click on that option  and  place a code .

 privatevoid dataGridView1_CellDoubleClick(object sender,  DataGridViewCellEventArgs e)
         {
 //For accessing data as rows with respected cells
            int id =  Convert.ToInt32(dataGridView1.Rows[e.RowIndex].Cells[0].Value);
           
  
       //Creating object for NewForm as nf   
  
         NewForm nf =  newNewForm(id);
          //Display it into another form
            nf.ShowDialog();
}
   

Then Design a NewForm as shown Below in the snapshot.

 //how to show data in the respected fields while click on the datagrid cell.place a code under newForm Load Event as below.
  
 //calling Global items
         SqlConnection con;
        SqlDataReader rdr;
        SqlDataReader rdr1;
        int nID;
    public NewForm(int ID)//calling constructors with one parametres as ID.
    {
            InitializeComponent();
            con = new SqlConnection("server=abc-pc1\\sqlexpress; uid=sa; password=sa; database=Mind");
            nID = ID;
}
  
 privatevoid NewForm_Load(object sender, EventArgs e)
         {
            con.Open();
 //Accessing commands from the database
            SqlCommand cmd = newSqlCommand("select * from Employee where Employee_id=" + nID, con);
 //accepting it into datareader
            rdr = cmd.ExecuteReader();
            rdr.Read();
            string a = rdr[0].ToString();
            txtID.Text = a;
            //taking itinto textfileld from the gridview
            txtName.Text = rdr[1].ToString();
            txtAddress.Text = rdr[2].ToString();
            txtPhoneno.Text = rdr[3].ToString();
            txtage.Text = rdr[4].ToString();
            rdr.Close();        }

Next step is to update rows from the new Form as shown in the snapshot as soon

as we click on any of the fields in the GridView u will see an another form will open

as shown below in the snapshot. Then we click on the update button and update

the records in the database.

Code for update the Records as shown below.

 privatevoid btbUpdate_Click(object sender, EventArgs e)
         {
            try
            {
 //show a messaage box wether we want to update a record or not.
                if (MessageBox.Show("Do you want to update record?", "update",  MessageBoxButtons.YesNo) == DialogResult.Yes)
                {
 //creating a command with the update query
                    SqlCommand cmd = newSqlCommand("UPDATE employee SET Employee_id='" + txtID.Text + "',Employee_name='" + txtName.Text + "',Employee_address='" + txtAddress.Text + "',Employee_phoneno='" + txtPhoneno.Text + "',Employee_age='" + txtage.Text + "'where Employee_id='" + nID + "'", con);
                    rdr1 = cmd.ExecuteReader();
                    con.Close();
                    this.Close();
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }