答案

1. Click the down arrow next to Dimensions in the data pane and select Create Parameter…
2. In the Create Parameter dialog, do the following and click OK:
   • Name the parameter. In this example I will call it "Select Start Date"<.li>
   • For Data Type, choose Date
   • For Allowable values, select Range
   • Check Step size and select 1 Months
3. Right-click [Select Start Date] in the data pane and select Show Parameter Control
4. Select Analysis > Create Calculated Field
5. In the Calculated Field dialog box that opens, do the following, and then click OK:
   • Name the calculated field. In this example, the calculated field is named "Date Filter"
   • In the formula field, create a calculation similar to the following:
     
     IF DATETRUNC('month', [Order Date]) >= [Select Start Date]
THEN [Order Date]
END
      
6. Drag [Date Filter] to the Filters shelf
7. In the Filter Field dialog, select Month / Year and click Next >
8. In the Filter dialog, do the following and click OK:
   • Navigate to the Condition tab
     • Select by formula
     • Type in the formula: NOT ISNULL(MIN([Date Filter]))
   • Navigate to the Top tab
     • Select By field
     • Select Bottom 2 by Date Filter Minimum