[c#] How to loop through each and every row, column and cells in a GridView and get its value

I have a GridView which is databound, on button_click I want to read the GridView row by row each column and read the value of each cell in a row and update a table in database? I also know how to check if that cell contains null.

I am trying something like this and got stuck:

protected void SAVE_GRID_Click(object sender, EventArgs e)
{
    int rowscount = GridView2.Rows.Count;
    int columnscount = GridView2.Columns.Count;
    for (int i = 0; i < rowscount; i++)
    {
        for (int j = 1; j < columnscount; j++)
        {
            // I want to get data of each cell in a row
            // I want to read the corresponding header and store
        }
    }       
}

As it's said by "Tim Schmelter" this is the best way : just change in it's code the seconde loop ( GridView2.Columns[i].Count by row.Cells.Count ) so it looks seem's that:

foreach(GridViewRow row in GridView2.Rows)
{
    for(int i = 0; i < GridView2.Columns.Count; i++)
    {
        String header = GridView2.Columns[i].HeaderText;
        String cellText = row.Cells[i].Text;
    }
}

thank you.

foreach (DataGridViewRow row in dataGridView1.Rows)
        {
            for (int i = 0; i < dataGridView1.Columns.Count; i++)
            {
                String header = dataGridView1.Columns[i].HeaderText;
                //String cellText = row.Cells[i].Text;
                DataGridViewColumn column = dataGridView1.Columns[i]; // column[1] selects the required column 
                column.AutoSizeMode = DataGridViewAutoSizeColumnMode.AllCells; // sets the AutoSizeMode of column defined in previous line
                int colWidth = column.Width; // store columns width after auto resize           
                colWidth += 50; // add 30 pixels to what 'colWidth' already is
                this.dataGridView1.Columns[i].Width = colWidth; // set the columns width to the value stored in 'colWidth'
            }
        }

foreach (DataGridViewRow row in GridView2.Rows)
            {
                if ( ! row.IsNewRow)
                {
                    for (int i = 0; i < GridView2.Columns.Count; i++)
                    {
                        String header = GridView2.Columns[i].HeaderText;
                        String cellText = Convert.ToString(row.Cells[i].Value);
                    }
                }
            }

Here Before Iterating for cell Values need to check for NewRow.