What kind of changes i can make to this code to protect against sql injection?
private void button1_Click(object sender, EventArgs e)
{
string query = "INSERT INTO person (name_,age_)VALUES('" + txtFirstname.Text + "','" + int.Parse(txtAge.Text) + "')";
DB.OpenConnection();
DB.SqlQuery = query;
DB.ExecuteQuery();
DB.CloseConnection();
}