Question

I’m not able to call take method from below linq query

var data = from tb in table.AsEnumerable()
           join ch in channelTable.AsEnumerable() on syskey equals (DateTime)ch["syskey"]
           orderby Convert.ToDouble(tb[(string.Format("Channel{0}_data",Convert.ToInt32(ch["Channel_No"])))]) descending                       
           select new
           {
               Channel_No = ch["Channel_No"],
               Channel_data = tb[string.Format("Channel{0}_data", Convert.ToInt32(ch["Channel_No"]))],
           };

How can I add Take(5) from above linq query?

Answer 1

As simply as:

var top5 = data.Take(5);

You can do it in the same statement, too, but it’s a bit ugly:

var data = (from tb in table.AsEnumerable()
            join ch in channelTable.AsEnumerable() on syskey equals (DateTime)ch["syskey"]
            orderby Convert.ToDouble(tb[(string.Format("Channel{0}_data",Convert.ToInt32(ch["Channel_No"])))]) descending                       
            select new
            {
                Channel_No = ch["Channel_No"],
                Channel_data = tb[string.Format("Channel{0}_data", Convert.ToInt32(ch["Channel_No"]))],
            }).Take(5);

Note that ordering by a string here probably doesn’t do what you want, unless your values are all single digit – would you really want channel3, channel2, channel10, channel1?

It’s a pretty odd query though – especially as your join doesn’t use anything from the first table…