Data insert one row even datagridview have multiple rows

See more:

C#

database

DataGridView

Hello Guys, i am facing a problem and problem is that i insert data in database using datagridview but it's only insert one row data even there is multiple row in datagridview.
please help me please

Thanks

What I have tried:

if (dataGridView1.Rows.Count < 0)
            {
                MessageBox.Show("Data Cannot be Insert", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                return;
            }
            else
            {
                for (int i = 0; i < dataGridView1.Rows.Count; i++)
                {
                    connection.Open();
                    OleDbCommand command = new OleDbCommand();
                    command.Connection = connection;
                    command.CommandText = "insert into [Sales Record] ([Product Name],[Price],[Quantity],[Customer Name],[Date],[Total Pro Price],[Bill Number],[Cash Sales],[Size])values('" + dataGridView1.Rows[i].Cells[0].Value.ToString() + "'," + dataGridView1.Rows[i].Cells[1].Value.ToString() + "," + dataGridView1.Rows[i].Cells[2].Value.ToString() + ",'" + dataGridView1.Rows[i].Cells[3].Value.ToString() + "',#" + dataGridView1.Rows[i].Cells[4].Value.ToString() + "#," + dataGridView1.Rows[i].Cells[5].Value.ToString() + "," + dataGridView1.Rows[i].Cells[6].Value.ToString() + ",'" + "Cash Sales" + "','" + dataGridView1.Rows[i].Cells[6].Value.ToString() + "');";
                    command.ExecuteNonQuery();
                    
                    
                    for (int j = 0; j < dataGridView1.Rows.Count; j++)
                    {
                        ad.InsertCommand = new OleDbCommand("UPDATE [Product Management] set [Quantity] = " + dataGridView1.Rows[j].Cells[7].Value + " where [Product Name] = '" + dataGridView1.Rows[j].Cells[0].Value + "'", connection);
                        
                        ad.InsertCommand.ExecuteNonQuery();
                        
                    }
                    printreceiptToken1();
                    
                    listBox2.Items.Clear();
                    listBox3.Items.Clear();
                    listBox4.Items.Clear();
                    listBox5.Items.Clear();
                    textBox2.Text = "";
                    textBox4.Text = "";
                    label1.Text = "";
                    textBox1.Text = "";
                    listBox1.SelectedIndex = 0;
                    MessageBox.Show("Data Inserted Successfully", "Insert", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    dataGridView1.Rows.Clear();
                    connection.Close();
                }
            }