Want to win a PS4? Go Premium and enter to win our High-Tech Treats giveaway. Enter to Win

x
?
Solved

get a sum from a sql table using linq to sql visual studio 2008 c#

Posted on 2012-03-28
3
Medium Priority
?
327 Views
Last Modified: 2012-03-29
I am trying to sum a field in a table.  If I use this method:

                        decimal? TotHrs2 = (from i in dc2.esna_JobAnalysis
                                   where i.emp_no == Emp.EmployeeId &&
                                   i.work_date == dt
                                   select i.hours).Sum();

I get this error:

"The null value cannot be assigned to a member with type System.Decimal which is a non-nullable value type."

This, of course works:

                        var GetHours = from i in dc.esna_JobAnalysis
                                                        where i.emp_no == Emp.EmployeeId &&
                                                        i.work_date == dt
                                                        select new { i.hours };

                        decimal TotHrs1 = 0;
                        foreach (var GH in GetHours)
                        {
                            TotHrs1 += GH.hours;
                        }

However, I'm hoping to avoid the loop.  Can't this be done with a .Sum using linq?  What am I doing wrong in the first example?

Thank you!
0
Comment
Question by:g_johnson
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
3 Comments
 
LVL 23

Accepted Solution

by:
wdosanjos earned 2000 total points
ID: 37782084
I'm assuming this is LINQ2SQL.  In that case, you would get that error when i.emp_no == Emp.EmployeeId && i.work_date == dt returns no records.  Please try the following to work around this issue:
decimal? TotHrs2 = (from i in dc2.esna_JobAnalysis
		   where i.emp_no == Emp.EmployeeId &&
		   i.work_date == dt
		   select (decimal?)i.hours).Sum();

Open in new window


I hope this helps.
0
 
LVL 4

Author Closing Comment

by:g_johnson
ID: 37782132
Thank you, that worked.  If I understand what you did, we are telling linq that if there are no records, return the resulting null as a nullable decimal so that it matches our declaration.  Is that about right?
0
 
LVL 23

Expert Comment

by:wdosanjos
ID: 37782240
Yes, that's correct.  I'm glad I was able to help.
0

Featured Post

Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

In order to hide the "ugly" records selectors (triangles) in the rowheaders, here are some suggestions. Microsoft doesn't have a direct method/property to do it. You can only hide the rowheader column. First solution, the easy way The first sol…
This article aims to explain the working of CircularLogArchiver. This tool was designed to solve the buildup of log file in cases where systems do not support circular logging or where circular logging is not enabled
In this video, Percona Solution Engineer Dimitri Vanoverbeke discusses why you want to use at least three nodes in a database cluster. To discuss how Percona Consulting can help with your design and architecture needs for your database and infras…
In this video, Percona Director of Solution Engineering Jon Tobin discusses the function and features of Percona Server for MongoDB. How Percona can help Percona can help you determine if Percona Server for MongoDB is the right solution for …

610 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question