Use Expressions in reports to control content and report appearance.Expressions are written in VB.
Take a look at the example
=IIF(Fields!Department.Value = "Development", "EmployeeReport", Nothing)
What this does is : Test the value of the Department field and return either a subreport name or a null (Nothing in Visual Basic).
Like this,based on conditions in expressions,you can assign the dataset or the columns to report .
Hope you get an idea with this article:
http://msdn.microsoft.com/en-us/library/ms157328.aspx[
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