SQL DataReader在循环中缺少一行

Question

运行以下代码时,它会遗漏一行.当我做一个files.Count它说有4行,但第4行没有存储数据.当我从SQL Manager中运行存储过程时,它返回所有4行和所有数据.有帮助吗？

            List<File> files = new List<File>();
            SqlConnection active_connection = new SqlConnection(m_connection_string);
            SqlCommand cmd = new SqlCommand();
            SqlDataReader dr = null;

            try
            {
                active_connection.Open();
                cmd.Connection = active_connection;
                cmd.CommandType = CommandType.StoredProcedure;
                cmd.CommandText = "dalsp_Select_Organization_Files";

                SqlParameter param;

                param = cmd.Parameters.Add("@p_organization_guid", SqlDbType.UniqueIdentifier);
                param.Value = new Guid(organization_guid);

                param = cmd.Parameters.Add("@p_file_type", SqlDbType.NVarChar, 50);
                param.Value = file_type;

                dr = cmd.ExecuteReader(CommandBehavior.CloseConnection);

                if (dr.HasRows)                    
                {                    
                    while (dr.Read())
                    {
                        File file = new File();
                        file.OrganizationGuid = dr["OrganizationGuid"].ToString();
                        file.FileGuid = dr["FileGuid"].ToString();
                        file.FileLocation = dr["FileLocation"].ToString();
                        file.FileName = dr["FileName"].ToString();
                        file.FileType = (FileTypeEnum)Enum.Parse(typeof(FileTypeEnum), dr["FileType"].ToString());
                        file.FileExtension = dr["FileExtension"].ToString();
                        file.FileDescription = dr["FileDescription"].ToString();
                        file.ThumbnailPath = dr["ThumbnailPath"].ToString();
                        files.Add(file);
                    }       
                }
                dr.Close();
                dr = null;

                active_connection.Close();
                cmd = null;

            }
            catch (Exception)
            {
                throw;
            }
            finally
            {
                if (active_connection.State != ConnectionState.Closed)
                {
                    active_connection.Close();
                    active_connection.Dispose();
                }
            }

            return files;

Answer 1

如果你说你的文件集有4个项目,但4个项目没有值,那你的意思是什么？它是null,对象没有数据,还是抛出索引超出范围异常？

你在做文件[4]或类似的东西吗？

for(int x = 1; x < files.length; x++)
{
     files[x]
}

那不行.记住C#中基于0的索引.

作为旁注,您可以通过执行以下操作来取消您的try catch语句:

using (SqlConnection connection = new SqlConnection(conn_string))
{
    connection.Open();
    using (SqlCommand cmd = new SqlCommand("SELECT * FROM MyTable", connection))
    {
         using (SqlDataReader dr = cmd.ExecuteReader())
         {
             return result;
         }
    }
}

using语句将保证读者和连接的处理(以及结束).