Here is the performance stats of the solution by Mark for TSQL Challenge20.
| Attempt | Start Time | Reads | Writes | CPU | Duration (Sec) |
| 1 | Apr 21 2010 11:29PM | 328 | 0 | 63 | 0.2050 |
| 2 | Apr 21 2010 11:59PM | 328 | 0 | 47 | 0.1730 |
| 3 | Apr 22 2010 12:29AM | 328 | 0 | 47 | 0.1520 |
| 4 | Apr 22 2010 12:59AM | 328 | 0 | 47 | 0.2870 |
| 5 | Apr 22 2010 1:29AM | 328 | 0 | 31 | 0.4290 |