Linq Query Limitations, more than one query fails

User 13592306

Hello: I simply want to write multiple queries to assign information.

            var q =
                from a1 in dt\_Jobs.AsEnumerable()
                orderby a1.Field("Customer")
                select a1.Field("Customer");
            var lstCustomer = q.Distinct().ToList();
            cboCustomer.DataSource = lstCustomer;

            q =
                from a1 in dt\_Jobs.AsEnumerable()
                orderby a1.Field("City")
                select a1.Field("City");
            var lstCity = q.Distinct().ToList();
            cboCity.DataSource = lstCity;

The first block works, the second fails. How can I achieve something like this?? Thanks!

Dave Kreskowiak

You're going to have to explain what "fails" means. Did it throw an exception? What was the message? Does something not work as expected? How so and under what conditions?

Asking questions is a skill CodeProject Forum Guidelines Google: C# How to debug code Seriously, go read these articles.
Dave Kreskowiak

User 13592306

I am trying to set the datasources for comboboxes. There is a datasource in the first, but not in the second. If I flip them around, I get the opposite effect.

User 13592306

Sorry for the confusion, there are errors. Exception thrown: 'System.FormatException' in mscorlib.dll Exception thrown: 'System.NullReferenceException' in ResourcePlanningC2.exe Exception thrown: 'System.InvalidCastException' in mscorlib.dll Exception thrown: 'System.NullReferenceException' in ResourcePlanningC2.exe Exception thrown: 'System.FormatException' in mscorlib.dll Exception thrown: 'System.NullReferenceException' in ResourcePlanningC2.exe Exception thrown: 'System.NullReferenceException' in ResourcePlanningC2.exe Exception thrown: 'System.FormatException' in mscorlib.dll The program '[12772] ResourcePlanningC2.exe' has exited with code -1 (0xffffffff). It must be hanging on some null values. Is there an easy way to handle this?

User 13592306

I think I got it, Thanks for the help!

var q =
from a1 in dt_Jobs.AsEnumerable()
orderby a1.Field("City")
where (a1.Field("City") != null)
select a1.Field("City");
var lstCity = q.Distinct().ToList();
cboCity.DataSource = lstCity;