here is my some coding which give me error string was not valid date and time
protected void btnsave_Click(object sender, EventArgs e)
{
string dfs = "26-06-1986";
DateTime dd = new DateTime();
dd = Convert.ToDateTime(dfs);
SqlCommand cmd = new SqlCommand("insert into dk values('"+ TextBox1.Text+ "','" + TextBox2.Text+ "')", con);
con.Open();
cmd.ExecuteNonQuery();
}