for (int i = 0; i < dataGridView.RowCount - 1; i++) //dataGridView.RowCount - 1 來獲取列數，-1是因為第一列是標題一般
{
try
{

//這些A、B、C等等，是用來存值，為以後SQL語句填值用，Row是行，Cell是列
string A= dataGridView1.Rows[i].Cells[0].Value.ToString();
string B = dataGridView1.Rows[i].Cells[1].Value.ToString();
string C = dataGridView1.Rows[i].Cells[2].Value.ToString();

//。。。。。。。看你需要多少行
SqlConnection sqlConnection = new SqlConnection(constr);
sqlConnection.Open();
SqlCommand cmd = sqlConnection.CreateCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "在這裡填需要的SQL語句";
cmd.ExecuteNonQuery();
sqlConnection.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}