Question

so using LINQ attempting to compare 2 values in the DB and select where the date is less than exactly a year today…so anything between 24/1/12 & 24/1/13 will be selected.

So i’ve got…

  var selectedObject =
            (from workstation in db.Work_Station
             join invoice in db.Invoices on workstation.id equals invoice.Site_Id
             where InvoiceDate < DateTime.Now.AddYears(-1)
             select workstation).Distinct().ToList();

this is producing a list but its not correct.
I’ve been playing about with the add years but can’t seem to get it..
Anyone have any ideas?
Thank You

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EDIT:
Hey everyone thank you for the quick response…i actually made a slight mistake, I want to return the value which has an invoice date of greater than exactly a year today…..So anything dated <= 24/1/12 will be returned. i have used ur suggestions to use…

DateTime OneYearAgo = DateTime.Now.AddYears(-1);

    var selectedObject  =
        (from workstation in db.Work_Station
         join invoice in db.Invoices on workstation.id equals invoice.Site_Id
          where InvoiceDate <= OneYearAgo
         select workstation).Distinct().ToList();

This returns a number of invoices…some of which are before the 23/1/12 and some of which are after.

Iv tried changing to where CurrentInvoiceDate >= OneYearAgo, which should return any dated between now and one year ago, but nothing is returned…what am i doing wrong? please advise…thank you

Answer 1

Your query matches your textual explanation. But both don’t match your sample data.

What you want is all data where the date is greater than or equal (not less than) a year ago:

var selectedObject =
            (from workstation in db.Work_Station
             join invoice in db.Invoices on workstation.id equals invoice.Site_Id
             where InvoiceDate >= DateTime.Today.AddYears(-1)
             select workstation).Distinct().ToList();

If it is possible that you have invoices with a date in the future, you also need to specify that the invoices should have a date less than or equal to today:

var selectedObject =
            (from workstation in db.Work_Station
             join invoice in db.Invoices on workstation.id equals invoice.Site_Id
             where InvoiceDate >= DateTime.Today.AddYears(-1)
                && InvoiceDate <= DateTime.Today
             select workstation).Distinct().ToList();

BTW: You want to use DateTime.Today instead of DateTime.Now.
Using DateTime.Now would not return invoices from the 24/1/12 that don’t have a time or that have a time earlier than now.