我想检索当前行中的前一行值,如下所示(Crystal Report 2008):
+------------+-----------------+----------+------------+----------------+
| Date       | PreviousBalance | Loan     | Collection | CurrentBalance |
+============+=================+==========+============+================|
| 14/02/2012 | 00.00           | 10000.00 | 00.00      | 10,000.00      |
| 15/02/2012 | 10,000.00       | 00.00    | 500.00     | 9,500.00       |
| 16/02/2012 | 9,500.00        | 00.00    | 500.00     | 9,000.00       |
| 18/02/2012 | 9,000.00        | 5,000.00 | 00.00      | 14,000.00      |
+------------+-----------------+----------+------------+----------------+
    
