这个LinQ有什么问题？

Question

这是我的Linq查询.这很好用.问题是如果表中没有任何姓氏,则结果中不显示该行.我想如果任何人没有姓,那么它将是User_Name = First Name +"".

var ShowFiles = from cm in db.Contact_Masters
                        join ta in db.Topic_Accesses on cm.Contact_ID equals ta.Contact_ID
                        join RelMess in db.Rel_Topics_Messages on ta.Topic_ID equals RelMess.Topic_ID
                        join Messages in db.Messages on RelMess.Message_ID equals Messages.Message_ID
                        join Files in db.Files on Messages.Message_ID equals Files.Message_ID
                        join FileType in db.Lkup_Files_Extensions on Files.TypeID equals FileType.TypeID
                        join FileVersion in db.File_Versions on Files.File_ID equals FileVersion.File_ID
                        join pcf in db.Contact_Personals on Messages.Contact_ID equals pcf.Contact_ID
                        where pcf.Personal_Type == new Guid("30102333-2104-40D7-8913-DC9048225D12") // Personal_Type = First Name ID
                        join pcl in db.Contact_Personals on Messages.Contact_ID equals pcl.Contact_ID
                        where pcl.Personal_Type == new Guid("9058F268-B707-4B0A-86E5-26E83A4BC1F5") // Personal_Type = Last Name ID 

                        where cm.Contact_ID == new Guid(ContactID) && ids.Contains(RelMess.Topic_ID)// parameters
                        && FileVersion.IsActive == true && Messages.IsActive == true && FileVersion.Version_ID == (from FileV in db.File_Versions
                                                                                                                   where FileV.File_ID == Files.File_ID 
                                                                                                                   && FileV.Message_ID == Messages.Message_ID 
                                                                                                                   && FileV.IsActive == true
                                                                                                                   select FileV.Version_ID).Max()
                        select new
                        {
                            File_Name = Convert.ToString(Files.File_Name),
                            Version_ID = Convert.ToString(FileVersion.Version_ID),
                            File_Size = Convert.ToString(FileVersion.File_Size),
                            Created = Convert.ToString(FileVersion.Created),
                            Type = FileType.Type,
                            File_URL = FileVersion.File_URL,
                            File_ID = Convert.ToString(FileVersion.File_ID),
                            User_Name = pcf.Value + " " + pcl.Value  
                        };

谢谢
Nahid

Answer 1

请尝试以下方法:

User_Name = pcf.Value + 
    (pcf.Value != null && pcf.Value.Trim() != string.Empty ? " " + pcl.Value : "")

编辑:删除了IsNullOrWhiteSpace的使用,谢谢Jacek