>>I have a dataset with 2 columns, Item and Quantity. The user can enter any value in Item, and any number in quantity. I would like to combine duplictes.
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>>Kevin, DataTable.DefaultView has a method called ToTable, and one of the overloads allows you to do the equivalent of a DISTINCT. Take a look at one of the overloads for ToTable
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>>So it could be as simple as...
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>>DataTable dtNewTable = dtOldTable.DefaultView.ToTable(true, "Column1", "Column2", etc.)
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>I have this:
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>DataTable dtNewTable = csCOSApp.ActiveProject.dsQuery.Tables[0].DefaultView.ToTable(true, new string[] { "Item", "Quantity" });
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>dtNewTable is the same as the source table. This doesn't work either:
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>DataTable dtNewTable = csCOSApp.ActiveProject.dsQuery.Tables[0].DefaultView.ToTable(true, "Item", "Quantity");
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>See this: www.marois-consulting.com/files/duplictes.jpg. You can see that the first 3 rows are duplicated. The result should be 1 row with a quantity of 15.

I think you either mis-represented your requirement or mis-understood the documentation. There are no duplicates in your jpg - the quantities are different. I assume that rather than removing duplicates you wanted to sum by Item ?