sql "not in" in Linq using datatable - sql

Question

How to convert sql query to linq using datatable.
select DISTINCT targeturl from internal where TargetURL NOT in (select DISTINCT url from Internal)
using this query, but still not getting the correct result.
var List1 = dt.AsEnumerable().Select(c => c.Field<string>("URL")).Distinct().ToList();
var List2 = dt.AsEnumerable().Select(c => c.Field<string>("TargetURL")).Distinct().ToList();
var Targetname = List2.Except(List1.ToList()).ToList();

Answer 1

You can also try populating an object then using the object to populate the datatable.
var data = Select(c => c.Field<string>("TargetURL")).Distinct().ToList();
Datatable dtMyTable = new Datatable();
dtMytable.Columns.Add("col1",typeof(string));
dtMytable.Columns.Add("col2",typeof(string));
dtMytable.Columns.Add("col3",typeof(string));
then populate the table
foreach (var item in data)
{
dtMytable.Rows.Add(data.col1,data.col2,data.col3);
}

Answer 2

I prefer to separate
first
dim query = (from u in Internal select u.url).distinct
Second
dim tmp = (from t in Interal where not query.contains(TargetURL) select TargetURL ).ToList
It's in VB.net but You can translate easily
And you can too distinct with group by request.

Answer 3

To write SELECT DISTINCT targeturl from internal where TargetURL NOT in (select DISTINCT url from Internal) in a linq lambda expression, you could use the following:
var result = Internal
.Select(a => a.TargetURL)
.Where(a => !Internal.Select(i => i.url).Distinct().Contains(a.TargetURL));
Or break it out a little as:
var distinctUrls = Internal.Select(i => i.url).Distinct();
var result = Internal.Select(a => a.TargetUrl)
.Where(a => !disctinctUrls.Contains(a.TargetUrl));
The above creates an IEnumerable of urls, which we use as an exclusion in the where predicate.