VB.NET数据网格计算（Visual Studio 2010）

In the datagrid table: calculate the difference between two columns with the result in third column (performed automatically during runtime). Null value is 0 in budget and cost columns. Budget - Cost = Difference. I am using Visual Studio 2010. If anyone knows how to do this in the designer, please let me know.Otherwise...In the datagrid table: calculate the difference