我的linq查询无法正常工作，我在做什么错？

Question

I have a datatable i create after reading in a txt file, once i have that datatable, i need to remove rows based on 1 column and a list of values List returnClass(), but after some testing, i found that my LINQ is removing more than expected... so not sure what im doing wrong with the code below.

At first i thought everything was good, because i was working with a large number of records and the numbers were going down with every pass, but now that im working with a small file to debug, i find out that its removing more than it should..

Here is my LINQ query:

// REMOVES ALL RECORDS WITH A CLASS THAT IS NON-LABEL CLASS                    
var query = from r in d.AsEnumerable()
            where !returnClass().Any(r.Field<string>("Column7").Contains)
            select r;

DataTable output = query.CopyToDataTable<DataRow>();
int dtoutputCount = output.Rows.Count;

ToCSV(output, ftype, "filteredclass");

Here is my list: (shorten to make this a simple question)

private List<string> returnClass()
{
    List<string> cl = new List<string>();
    cl.Add("7");
    cl.Add("72");
    return cl;
}

My datatable has 100 rows, the column7 has number in it, type string, i need to find each row that has the exact numbers in my list, so if it finds a 7, i dont want it and if it find a 72 i dont want it. BUT if there is a 75, or 17 or 127 those need to stay. And the query above is removing those because it contains the number 7.

How can i remove based on exact matches?

Answer 1

I think the problem is that you are actually looking to see if any value in your returnClass() list contains the value found in column7 . Inside your Any function you are using String.Contains , and I'm guessing you expect this is a List.Contains or something along those lines.

Try this instead (untested):

// REMOVES ALL RECORDS WITH A CLASS THAT IS NON-LABEL CLASS                    
var query = from r in d.AsEnumerable()
            where !returnClass().Contains(r.Field<string>("Column7"))
            select r;

DataTable output = query.CopyToDataTable<DataRow>();
int dtoutputCount = output.Rows.Count;

ToCSV(output, ftype, "filteredclass");