C# chart

private void button_Inquiry_Click(object sender, EventArgs e)
{
//MessageBox.Show(dateTimePicker1.Value.ToString());
try
{
string strConn = @"data source=PANLEE-PC;initial catalog=DB15728;integrated security=true";
SqlConnection conn = new SqlConnection(strConn);
//conn.Open();
string sql = "select data_value,data_time from FrequencyOfNode_1 where data_DateTime Between '" + dateTimePicker1.Value + "'" + "and '" + dateTimePicker2.Value + "'";
SqlCommand cmd = new SqlCommand(sql, conn);
chart5.DataSource = cmd;
//chart5.Series[0].XValueMember = DateTime.Now.ToShortTimeString();
chart5.Series[0].XValueMember = "data_time";    //DateTime 类型数据在须数据库中存为字符型
chart5.Series[0].YValueMembers = "data_value";
chart5.DataBind();
conn.Close();

}
catch { MessageBox.Show("ERROR"); }
}