Question

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Cannot add an entity with a key that is already in use (LINQ)

I have googled a lot on this issue and found many people facing the same issue. but could get through it yet. many solutions were posted but no gain.

I have written a LINQ query which retrieve some 38 records and using foreach loop i insert those records in other table as per the code.

var Results =  (from p in (from d in compact.CURRENT_STATUS
                                                   where QtrEndDate >= d.ValidStartDate && QtrEndDate <= d.ValidDueDate && d.LocationCode == EmployeeLocation && d.DeptCode == selecteddept
                                            select new
                                            {
                                                loccode = d.LocationCode,
                                                taskcode = d.TaskCode,
                                                deptcode = d.DeptCode,
                                                flag = d.Flag,
                                                startdate = d.ValidStartDate,
                                                duedate = d.ValidDueDate,
                                                remarks = d.Remarks,
                                                content = d.UploadDocContent,
                                                title = d.UploadDocTitle,
                                                type = d.UploadDocType
                                            }).Union(from i in compact.HISTORY_STATUS
                                                     where QtrEndDate >= i.ValidStartDate && QtrEndDate <= i.ValidEndDate && i.LocationCode == EmployeeLocation && i.DeptCode ==  selecteddept
                                                     select new
                                                     {
                                                loccode = i.LocationCode,
                                                taskcode = i.TaskCode,
                                                deptcode = i.DeptCode,
                                                flag = i.Flag,
                                                startdate = i.ValidStartDate,
                                                duedate = i.ValidEndDate.Date,
                                                remarks = i.Remarks,
                                                content = i.UploadDocContent,
                                                title = i.UploadDocTitle,
                                                type = i.UploadDocType
                                                     }) select p);





                        foreach (var item in Results)
                        {
                            REPORT_TABLE RT = new REPORT_TABLE();
                            {

                                RT.LocationCode = item.loccode;
                                RT.TaskCode = item.taskcode;
                                RT.DeptCode = item.deptcode;
                                RT.Flag = item.flag;
                                RT.ValidStartDate = item.startdate;
                                RT.ValidDueDate = item.duedate;
                                RT.Remarks = item.remarks;
                                RT.UploadDocContent = item.content;
                                RT.UploadDocTitle = item.title;
                                RT.UploadDocType = item.type;
                                RT.SubmittedBy = (Session["username"]).ToString();
                                RT.SubmittedByIP = (Session["IP"]).ToString();
                                RT.SubmittedOn = System.DateTime.Now;
                                RT.ReportID = RHqueryFind.ReportID;
                                RT.AsOnDate = QtrEndDate;
                            }
                            compact.REPORT_TABLEs.InsertOnSubmit(RT);  
                            compact.SubmitChanges();
                        };

But i do get the error Cannot add an entity with a key that is already in use in the last line i.e SubmitChanges.

In one of the solution i found a line of code to be added as RefreshMode but this could not solve my problem.

Answer 1

I think you have to remove Primary key of your column. Create new column i.e. SerialNo and set it as primary key with Identity Specification.

I got same problem i.e. Cannot add an entity with a key that is already in use but when I removed the primary key of column which I was inserting the value and create a new column with Primary key and Identity Specification. Problem solved