Question

I have a List of Customers

List<Customers> cust = new List<Customers>(); cust.Add(new Customers(){ID=1, Name='Sam', PurchaseDate=DateTime.Parse('01/12/2008')}); cust.Add(new Customers(){ID=2, Name='Lolly' PurchaseDate=DateTime.Parse('03/18/2008')}); 

I want to show 2 seperate results like:

Purchases by Customer in Yr // Grouping by yr and display id,name
Purchases by Customer in Yr – Month // Grouping by yr then month and display id,name

Also What if i want to order the yr?

Update:

Just one more addition. If I have a field called ‘Status’ in the Customer class with either of these values ‘Y’, ‘N’, ‘C’ standing for yes, no and cancel how will i create a query to give ratio in %

Y – 20% N – 30% C – 50%

Answer 1

Grouping by year:

var groupByYear = customers.GroupBy(customer => customer.PurchaseDate.Year);  foreach (var group in groupByYear) {     Console.WriteLine('Year: {0}', group.Key);     foreach (var customer in group)     {         Console.WriteLine('{0}: {1}', customer.ID, customer.Name);     } } 

Grouping by year and month:

var groupByYearMonth = customers.GroupBy(customer =>       new DateTime(customer.PurchaseDate.Year, customer.PurchaseDate.Month, 1)); foreach (var group in groupByYear) {     Console.WriteLine('Year/month: {0}/{1}', group.Key.Year, group.Key.Month);     foreach (var customer in group)     {         Console.WriteLine('{0}: {1}', customer.ID, customer.Name);     } } 

Ordering:

var ordered = customers.OrderBy(customer => customer.PurchaseDate.Year); 

All of these use ‘dot notation’ instead of query expressions because they’re so simple – but you could use a query expression if you wanted to.

EDIT: For the status part, just use David B’s answer.