Question

i have a datatable which contains “InvalidCodes”.

Before uploading the data to database(data is still in datatable), i want to perform linq on the datatable to remove Invalid entries and move them in another datatable

datatable allEntries ( entries yet to be uploaded in database)
datatable InvalidCodes(single column datatable – retrieved from database)
datatable invalidEntries

right now “allEnties” contains valid entries and invalid entries. the linq query on “allEntries” should move the nonexistend code entries to invalidEntries datatable.

plz help me perform this.

below is the query i formed but its not valid

string query = "select [CityCode] from [StateCity] ";
DataTable citylist = getDataTableFromSelect(query);

var result = from myrow in inputDt.AsEnumerable()
             where !myrow.Field<string>("CityCode").Contains(from myrow2 in citylist.AsEnumerable() select myrow2.Field<string>("CityCode") )
             select myrow;

Answer 1

I’d make a HashSet for the invalid city codes – this will allow the code to quickly/efficiently identify which of the codes are in the invalid set.

e.g. something like:

var invalidCityCodes = from myrow2 in citylist.AsEnumerable()
                       select myrow2.Field<string>("CityCode");

var invalidCityCodeHashSet = new HashSet<string>(invalideCityCodes);

var result = from myrow in inputDt.AsEnumerable()
             where !invalidCityCodeHashSet.Contains(myrow.Field<string>("CityCode"))
             select myrow;