[Help] How to insert data from the textBox to MySQL Database in C#

[junharefa]

I want to insert data from the textBox to MySQL Database, but the data can't be inserted into the database. Here is the code snipped that I have created.
private void button6_Click(object sender, EventArgs e)
{
string connectionSQL = "server=localhost;database=db_junisman_kulit;uid=root;password=;";
MySqlConnection conn = new MySqlConnection();
double no_simpan = 0;
try
{
conn.Open();
MySqlCommand cmd = new MySqlCommand("INSERT INTO tb_backorder (no_simpan,tanggal_simpan,jumlah_rata_rata,lead_time,ongkos_pesan,harga_barang,ongkos_simpan,ongkos_kekurangan_barang,jumlah_pemesanan,reorder_point,safety_stock,persentase_pelayanan,ongkos_total) VALUES ('" + no_simpan + "', '" + DateTime.Now.ToString("yyyyMMdd") + "', '" + textBox1.Text + "', '" + textBox3.Text + "', '" + textBox5.Text + "', '" + textBox6.Text + "', '" + textBox7.Text + "', '" + textBox8.Text + "', '" + textBox9.Text + "', '" + textBox10.Text + "', '" + textBox11.Text + "', '" + textBox12.Text + "', '" + textBox13.Text + "')", conn);
conn.Close();
}

catch (MySqlException ex)
{

MessageBox.Show("Can't connect to database\n" + ex.ToString());
}
}

for no_simpan, this data is not from the textBox but a sequence number that is automatically ordered if the data is stored to the database.

and for tanggal_simpan is the date when the data is stored to the database.
How do I write the correct code to insert the data from the textBox into the MySQL database? I use a MySQL database.

I have attached form display and tb_backorder picture below
Thank You in Advance,