LINQ Query in DataTable

Question

I have a DataTable named dt. It has two Columns named atype_code and module. Now i need to query a module based on specific atype_code.

Here is the code i wrote but not working.

DataTable dt = GetATypeCodeList();
var accType = (from myAccType in dt.AsEnumerable()
           where myAccType.Field<string>("atype_code") == aTypeCode.Trim()
           select myAccType.Field<string>("module"));

acctype is a System.Data.EnumerableRowCollection<System.String>.

Answer 1

Since you've said that you

need to query a module based on specific atype_code

, i assume that you want only one module with the given atype_code.

Then you should either use Single/SingleOrDefault or First/FirstOrDefault.

String firstModule = dt.AsEnumerable()
                       .Where(r => r.Field<string>("atype_code") == aTypeCode.Trim())
                       .Select(r => r.Field<string>("module"))
                       .FirstOrDefault();
// or
String singleModule = dt.AsEnumerable()
                       .Where(r => r.Field<string>("atype_code") == aTypeCode.Trim())
                       .Select(r => r.Field<string>("module"))
                       .SingleOrDefault();

Enumerable.Single throws an exception if there is more than one matching element. That can be useful to validate the data.

Edit:

Here's the query-syntax:

IEnumerable<String> modules =  
    from myAccType in dt.AsEnumerable()
    where myAccType.Field<string>("atype_code") == aTypeCode.Trim()
    select myAccType.Field<string>("module");
String module = modules.FirstOrDefault(); // returns null if no matching modules were found