LinQ query help regarding duplicates

[Rajiv_Mulchandani (Rajiv)]

u will get a datatable with duplicates removed. post which you can use a simple linqu to get the results based on effective date.

[VivekKumar0707 (Vivek Kumar)]

@Biswas_Ishan

(From row In AdditionsReportDT.AsEnumerable()
                   Group row By associateID = row.Field(Of String)("Associate ID") Into Group = Group
                   Let maxDateRow = If(Group.Count() = 1,
                                       Group.First(),
                                       Group.OrderByDescending(Function(r As DataRow) DateTime.ParseExact(r.Field(Of String)("Effective Date"), {"MM-dd-yyyy", "MM/dd/yyyy"}, CultureInfo.InvariantCulture)).First())
                   Select maxDateRow).CopyToDataTable()

Your LINQ query seems mostly correct. However, there are a few adjustments needed

1. You need to specify the date formats for parsing correctly.
2. “DateTime.ParseExact” method requires an array of formats, not just a single format string.

So the Query goes like this

var result = (from row in AdditionsReportDT.AsEnumerable()
group row by row.Field(“Associate ID”) into grp
let maxDateRow = grp.OrderByDescending(r => DateTime.ParseExact(r.Field(“Effective Date”), new string { “MM-dd-yyyy”, “MM/dd/yyyy” }, CultureInfo.InvariantCulture)).First()
select maxDateRow).CopyToDataTable();