#### How to construct an aggregate expression in the expression builder

1. In Expression Builder, under Category, select BIRT Functions. Sub-Category displays the classes of functions that BIRT defines.
2. Select Total to display the aggregate functions.
3. Double-click the aggregate function that you want to use. The function appears in the expression area of Expression Builder.
4. Within the parentheses, ( ), of the function, specify the data-set field (or column binding that refers to the data-set field) whose values you want to aggregate:

1. Under Category, choose Available Data Sets or Available Column Bindings.
2. Under Sub-Category, choose the data set that contains the field, or the element that contains the column bindings.
3. Double-click the data-set field or column binding to insert it between the parentheses of the aggregate function.

5. Choose OK to save the expression.