在C＃中执行sql命令时出错

Question

I am using asp.net with c# and there exist an error in these line of codes.

protected void btnsubmit_Click(object sender, EventArgs e)
{
    string type = "c";
    string FID = Session["FID"].ToString();
    SqlConnection cn = new SqlConnection();
    SqlCommand cmd = new SqlCommand();
    //int str_diff = Convert.ToInt32(ConfigurationManager.AppSettings["Difference"]);
    cn.ConnectionString = @"Data Source=BOPSERVER;Initial Catalog=Project;Integrated Security=True";
    cn.Open();
    cmd.CommandText = "update TrackingFaculty_det SET Type=@Type WHERE (FID=@FID) and DATEDIFF(d,TrackingFaculty_det.LastUpdateDate,GETDATE())>60";
    cmd.Parameters.Add("@FID",SqlDbType.VarChar,10);
    cmd.Parameters["@FID"].Value = FID;
    cmd.Parameters.Add("@Type", SqlDbType.VarChar, 1);
    cmd.Parameters["@Type"].Value = type;
    cmd.ExecuteNonQuery();
    cn.Close();

    Response.Redirect("~/Faculty/Personaldet.aspx");
}

Answer 1

您尚未将连接设置为命令

cmd.Connection = cn;

Answer 2

You need to assign the SqlConnection to the SqlCommand . As an additional suggestion I would wrap the connection in a using block to ensure it is correctly disposed in the case of an exception.

using (SqlConnection cn = new SqlConnection(@"Data Source=BOPSERVER;Initial Catalog=Project;Integrated Security=True") 
{
    cn.Open();
    SqlCommand cmd = new SqlCommand("update TrackingFaculty_det SET Type=@Type WHERE (FID=@FID) and DATEDIFF(d,TrackingFaculty_det.LastUpdateDate,GETDATE())>60", cn);
    cmd.Parameters.Add("@FID",SqlDbType.VarChar,10);
    cmd.Parameters["@FID"].Value = FID;
    cmd.Parameters.Add("@Type", SqlDbType.VarChar, 1);
    cmd.Parameters["@Type"].Value = type;
    cmd.ExecuteNonQuery();
}

Answer 3

    SqlCommand cmd = new SqlCommand("update TrackingFaculty_det SET Type=@Type WHERE (FID=@FID) and DATEDIFF(d,TrackingFaculty_det.LastUpdateDate,GETDATE())>60", cn);
    cmd.Parameters.Add("@FID",SqlDbType.VarChar,10);
    cmd.Parameters["@FID"].Value = FID;
    cmd.Parameters.Add("@Type", SqlDbType.VarChar, 1);
    cmd.Parameters["@Type"].Value = type;
    cmd.ExecuteNonQuery();