Question

我是asp.net和sql server的新手我写了一个代码来设置我的模型，我只需要一行，所以我写了这段代码：

我的模特

public class FullPackages
{
    public int Id { get; set; }
    public int TypeId { get; set; }

    [Display(Name = "Package Type")]
    public string TypeName { get; set; } 
    public int AllowedSMS { get; set; }

    [Display(Name = "Time Span in Days")]
    public int? TimeSpan { get; set; }
    public decimal Price { get; set; }
}

我的方法

    public ActionResult PackageDetails(int id = 0)
    {
        string sqlString = "select top 1 tblPackages.*, tblPackageTypes.Name from tblPackages join tblPackageTypes on tblPackages.TypeId = tblPackageTypes.Id where tblPackages.Id = "+id;

        SqlConnection con = new SqlConnection(cnxn); // cnxn is defined
        SqlCommand cmd = new SqlCommand(sqlString, con);
        SqlDataReader dsr;
        FullPackages package = new FullPackages();


            con.Open();

            dsr = cmd.ExecuteReader();  // this returns null value

                package.Id = dsr.GetInt32(0);
                package.TypeId = dsr.GetInt32(1);
                package.TypeName = dsr.GetString(5);
                package.AllowedSMS = dsr.GetInt32(2);
                package.TimeSpan = dsr.IsDBNull(3) ? 0 : dsr.GetInt32(3);
                package.Price = dsr.GetDecimal(4);
            con.Close();

        return View(package);
    }

当我从sqlString中删除top 1时，它返回数据库中的值但是当我保留top 1时它返回null。当我在sql server中检查与top 1相同的sql时Mgmt Studio它返回单行..为什么会这样？请帮帮我......

Answer 1

您可以执行以下操作而不是代码：

string sqlString = "select top 1 tblPackages.*, tblPackageTypes.Name from tblPackages join tblPackageTypes on tblPackages.TypeId = tblPackageTypes.Id where tblPackages.Id = " + id;
        SqlConnection con = new SqlConnection(cnxn); // cnxn is defined 

        SqlDataAdapter sda = new SqlDataAdapter(sqlString, con); 
        DataTable dt = new DataTable(); 
        sda.Fill(dt);
        FullPackages package = new FullPackages();

        package.Id = Convert.ToInt32(dt.Rows[0][0]); 
        package.TypeId = Convert.ToInt32(dt.Rows[0][1]);
        package.AllowedSMS = Convert.ToInt32(dt.Rows[0][2]); 
        package.TimeSpan = !DBNull.Value.Equals(dt.Rows[0][3]) ? Convert.ToInt32(dt.Rows[0][3]) : 0;
        package.Price = Convert.ToInt32(dt.Rows[0][4]);

sql server查询返回null

1 个答案: