select column from dataset using LINQ

Question

I am absolutely new to linq query, please help with this query, dataset has fields:

Name Value Client_owner.

I want to select Value if name == "searchtext"

DataTable results = (from d in ((DataSet)_MyDataset).Tables["Records"].AsEnumerable()
                     orderby d.Field<string>("Name") ascending
                     where d["Name"].ToString().ToLower().Contains(ProjectName.ToLower())
                     select d??).CopyToDataTable();

Solution

var query = (from d in _MyDataset.Tables["Records"].AsEnumerable()
                                 where d.Field<String>("Name").Equals("searchText", StringComparison.CurrentCultureIgnoreCase)
                                 select d).OrderBy(x => x.Field<String>("Name"));

if (query.Count() != 0) { DataTable result = query.CopyToDataTable(); }

if _MyDataSet is a DataSet object then the extra cast is not needed in your example.

then create an extension method to create a filtered data table:

public static class DataTableExtensions
{
    public static DataTable ReturnColumn(this DataTable dataTable, ICollection<String> fieldNames)
    {
        if (fieldNames.Count > 0)
        {
            for (int i = 0; i < dataTable.Columns.Count; i++)
            {
                DataColumn col = dataTable.Columns[i];
                if (!fieldNames.Contains(col.ColumnName))
                {
                    dataTable.Columns.Remove(col);
                    i--;
                }
            }
        }

        return dataTable;
    }
}

you can then filter your datatable like so:

results.ReturnColumn(new List<String> { "Value" });

which will return a data table with only the column "Value"

Comments

[Admin]

Thanks, but why is is so complicated, is there any way in linq query to select a field? Select value

[Admin]

Please so let me know how to access this field in this stmt: foreach (ListItem item in projList) { if (item.Text.IndexOf(results.Field(value)???.StringComparison.‌​CurrentCultureIgnore‌​Case) > -1) { returnItems.Add(item); } }

[Ahmad Mageed]

I suggest breaking the query down rather than trying to chain too many things together (read up on the Law of Demeter en.wikipedia.org/wiki/Law_of_Demeter). The CopyToDataTable() call will throw an InvalidOperationException if no rows are returned by the query. Assign the query separately, then if (query.Count() != 0) { DataTable result = query.CopyToDataTable(); }.

[Admin]

Sorry, but I don't know how to assign the query separately? Also I just want to select the column "Value", isn't there someting in linq query to select column? Like in SQL Select Name, adress, location from table?