Question

I have a LINQ query in C# which runs on a datatable that is generated from a SQL Server exectution:

DataTable dtSubjects = db.ExecuteDataTable();
            var subjectsWithoutParent = from row in dtSubjects.AsEnumerable() 
                                        where row["ParentID"] != DBNull.Value && row.Field<int>("ParentID") == 0 
                                        select row;

Afterwards, there’s a foreach that should run on each DataRow returned from the the LINQ. However, the foeach code does not run.

foreach (DataRow rowSubject in subjectsWithoutParent)
            {
                rowSubject["ParentID"] = DBNull.Value;
            }

The Datatable has rows on it, and as far as I can tell subjectsWithoutParent gets at least one row from the LINQ.

Any ideas?

Answer 1

Try

IEnumerable<DataRow> subjectsWithoutParent = (from row in 
dtSubjects.AsEnumerable()                                          
where row["ParentID"] != DBNull.Value && 
row.Field<int>("ParentID") == 0                                          
select row).ToList<DataRow>();

and then check subjectsWithoutParent.Any() is it retrieving data or not?