从linq获取不同的价值

Question

I have ad-hoc query which is used generate Gridview.DataSource=DataTable,and I'm trying to get distinct(No duplicates) results from based on the ID(ActionID) but the duplicates still exist.Using the distinct keyword in the select linq statement seems have no effect.(Still struggling with linq).Is there another way to do this?

    DataTable dtSerachResults = new DataTable(); 
string qryStr = @"SELECT Distinct [ActionID]
                                    , [Title],convert(varchar(11),[DateRaised],109)as  DateRaised
                                , convert(varchar(11)
                                ,[TargetCompletionDate] ,109) as TargetCompletionDate 

                                ,dbo.fn_GetPersonelName(fk_PersonnelID) as Responsible
                                ,dbo.fn_GetStatusNameByID(fk_StatusID)   as [Status]
                                ,dbo.fn_GetClientNameByID(fk_CustomerID)as Client
                                ,dbo.fn_GetLocationByLocationID(fk_LocationID) as Location
                                ,dbo.fn_GetClientNameByID(fk_CustomerID) as Client
                                ,dbo.fn_GetSourceNameByID(fk_SourceID)as [Source]
                                , dbo.fn_GetPersonelName(fk_RaisedBy) as RaisedBy
                                ,dbo.fn_GetPersonelName(dbo.fn_GetActionItemPrimaryResponsibleEmployeeID([ActionID]))as [Primary]
                               ,DATEDIFF(DD,DateRaised,GETDATE()) as Diff
                                ,IsApproved=
                                case IsApproved 
                                    when 1 then 'Approved'
                                    when 0 then 'Rejected'
                                    ELSE  'Waiting'
                                End 
                        FROM [ActionTrackerTable] att
                        inner join [dbo].[ActionResponsibilitiesTable] art on art.fk_ActionID=att.[ActionID] ";

                //title
                if (!string.IsNullOrEmpty(ActionTracker.Title))
                {
                    qryStr += " and Title like '" + ActionTracker.Title + "%'";
                }

                //dateraised
                if (ActionTracker.DateRaised > DateTime.MinValue)
                {
                    qryStr += " and DateRaised >= '" + ActionTracker.DateRaised.ToString() + "'";
                }
                //targetgedate
                if (ActionTracker.TargetCompletionDate > DateTime.MinValue)
                {
                    qryStr += " and TargetCompletionDate>= '" + ActionTracker.TargetCompletionDate.ToString() + "'";
                }

                //Location
                if (ActionTracker.Location != null)
                {
                    qryStr += " and   fk_LocationID= " + ActionTracker.Location.LocationID.ToString() + "";
                }
                //client
                if (ActionTracker.Customer != null)
                {
                    qryStr += " and   fk_CustomerID= " + ActionTracker.Customer.CustomerID.ToString() + "";
                }
                //source
                if (ActionTracker.Source != null)
                {
                    qryStr += " and   fk_SourceID= " + ActionTracker.Source.SourceID.ToString() + "";
                }
                //approval status
                if (ActionTracker.SearchApprovalStr == "Approved")
                {
                    qryStr += " and   IsApproved= " + 1.ToString();
                }
                if (ActionTracker.SearchApprovalStr == "Rejected")
                {
                    qryStr += " and   IsApproved= " + 0.ToString();
                }

                if (ActionTracker.SearchApprovalStr == "Waiting")
                {
                    qryStr += " and   IsApproved is null";
                }
                //status
                if (ActionTracker.Status !=null)
                {
                    if (ActionTracker.Status.StatusID>0)
                    {
                        qryStr += " and   [fk_StatusID]= "+ActionTracker.Status.StatusID.ToString();
                    }
                }

                //ref num
                if (ActionTracker.ActionTrackerID > 0)
                {
                    qryStr += " and   ActionID = " + ActionTracker.ActionTrackerID.ToString();
                }

                if ( (strSearchTerm)=="All" ||(strSearchTerm)=="Select Employee"  )
                {                                )";

                    //rrun qry
                     //add the order str
                     qryStr += " order by ActionID desc ";
                     System.Data.SqlClient.SqlConnection sqlConn = new System.Data.SqlClient.SqlConnection();
                     using (sqlConn = ConnectionClass.CreateConnection.publicGetConn())
                     {
                         sqlConn.ConnectionString = ConnectionClass.CreateConnection.getConnectionString();
                         sqlConn.Open();
                         if (sqlConn.State == System.Data.ConnectionState.Open)
                         {
                             using (System.Data.SqlClient.SqlCommand sqlCMD = new System.Data.SqlClient.SqlCommand())
                             {
                                 sqlCMD.CommandText = qryStr;
                                 sqlCMD.CommandType = System.Data.CommandType.Text;
                                 sqlCMD.Connection = sqlConn;
                                 //parameters
                                 //no 1 is reponsbile
                                 //sqlCMD.Parameters.AddWithValue("@responsibleEmployeeID", responsibleEmployeeID);

                                 //return value

                                 System.Data.SqlClient.SqlDataReader rdr = sqlCMD.ExecuteReader();
                                 //get dataset
                                 DataSet DS = new DataSet();
                                 //load dataset in table
                                 DataTable dt = new DataTable();
                                 dt.Load(rdr);

                                 DS.Tables.Add(dt);
                //get Distinct rows based on the Thier rows 


 var q2 = (from dr in dt.AsEnumerable() select dr).Distinct().CopyToDataTable();
                                     dtSerachResults = (from dr in dt.AsEnumerable() select dr).Distinct().CopyToDataTable();


                }


            }

Answer 1

Distinct affects all columns, not just the column it precedes. You could group the rest of the columns ( and add appropriate aggregate functions to the select list). Its going to depend a lot on how your data looks.