Question

Ok, the more I use LINQ, the more I like it! I recently found myself working in some legacy code at work. It is your classic DataSet and DataTable rich application. Well, when adding a bit of functionality I found myself really wanting to just query the rows of a DataTable for the results I was looking for.

Let me repeat that… instead of looping and adding to a temp collection, I just wanted to ask the Rows collection for what I needed. No looping, no temp variables, just give me what I want.

var customerOrderIds = table.Rows.Cast<DataRow>()    .Where(x => (string)x['CUSTOMER_ID'] == customerId)    .Select(x => (string)x['CUSTOMER_ORDER_ID'])    .Distinct(); 

My question is whether or not this is a good thing, or am getting carried away with LINQ? It does seem to me that this declarative style of pulling a subset of data out of a collection is a good thing and more readable in the end. But then again, maybe I’m just smitten 🙂

Answer 1

One other observation; if you aren’t using typed datasets, you might also want to know about the Field<> extension method:

    var customerOrderIds = table.Rows.Cast<DataRow>()        .Where(x => x.Field<string>('CUSTOMER_ID') == customerId)        .Select(x => x.Field<string>('CUSTOMER_ORDER_ID'))        .Distinct(); 

Or using the query syntax:

   var customerOrderIds = (         from row in table.Rows.Cast<DataRow>()         where row.Field<string>('CUSTOMER_ID') == customerId         select row.Field<string>('CUSTOMER_ORDER_ID')      ).Distinct(); 

I’m not saying it is better or worse – just another viable option.

(Actually, I don’t use DataTable very much, so YMMV)