Quote:And because I try to do that on a second form, the code can't find dataGridView1.
Refer to this series of tips on how to pass information between forms Transferring information between two forms, Part 1: Parent to Child
string query = "INSERT INTO ticket.support (titel, beschreibung, kategorie, ersteller, bearbeiter, email, abteilung) " +
"Values('" + textBox1.Text + "', '" + textBox2.Text + "', '" + comboBox1.Text + "', '" + textBox4.Text + "', '" + textBox5.Text + "', '" + textBox8.Text + "', '" + comboBox3.Text + "')";
You are using string concatenation to create your query. Don't do that. Refer SQL Injection | OWASP
] and use parameterised queries