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Error when using SubQuery and OrderBy
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johneevo View Drop Down
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Joined: 03-Dec-2007
Location: United States
Posts: 8 		Post Options Post Options   Quote johneevo Quote  Post ReplyReply Direct Link To This Post Topic: Error when using SubQuery and OrderBy
    Posted: 10-Dec-2007 at 6:49am
I'm receiving a "Failed to compare two elements in the array." error when using a query that has a subquery and order by clauses. I am ordering by 5 columns but the one that is causing the problem is an int32 column that contains NULLs.

If I suppress query inversion I do not get an error but the data is not sorted correctly.

If I leave query inversion on and do not sort by the problem column, then I do not get an error and the data is sorted correctly.

The inner exception that I get with the above mentioned query is:
"At least one object must implement IComparable."

Let me know if you need more info on this error.
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davidklitzke View Drop Down
IdeaBlade
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Joined: 14-Jun-2007
Posts: 715 		Post Options Post Options   Quote davidklitzke Quote  Post ReplyReply Direct Link To This Post Posted: 10-Dec-2007 at 8:56am
This appears to be a .NET problem, not a DevForce problem.  If you search the web, you can find a few links to articles which discuss this problem.
 
Try:
 
 
 
 
Perhaps, one of your Entities needs to override IComparable (as shown in the example below):
 
 public override int CompareTo(Object pObject) {
   Employee emp = pObject as Employee;
   if (emp == null) return 1;
   return this.LastName.CompareTo(emp.LastName);
  }
 
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