RadGrid is a bound control and being such it does all it's operations like filtering and sorting on a data level. This means that you can apply a sort or filter expression for a certain field. In the particulars case we have two fields LastName and FirstName and we can sort/filter by them. But RadGrid can not sort/filter by their concatenated value because it is not included in the grid's data source. That said you can resolve the problem by including a filed which represents the concatenated string value in the data source. This will allow you to manipulate the data by using the built-in mechanism of the grid.
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