Hiiya All，
尝试弄清楚如何使用SQL告诉我一个人在约会之前连续工作了多少天。
来源
+----------+---------+-----------+------------+
| Forename | Surname | EMP_Num | Shift Date |
+----------+---------+-----------+------------+
| John | Kerry | 0111 | 2017-09-28 |
+----------+---------+-----------+------------+
| John | Kerry | 0111 | 2017-09-29 |
+----------+---------+-----------+------------+
| John | Kerry | 0111 | 2017-09-30 |
+----------+---------+-----------+------------+
| John | Kerry | 0111 | 2017-10-02 |
+----------+---------+-----------+------------+
| John | Kerry | 0111 | 2017-10-03 |
+----------+---------+-----------+------------+
| Bill | Kerry | 0112 | 2017-09-28 |
+----------+---------+-----------+------------+
| Bill | Kerry | 0112 | 2017-09-29 |
+----------+---------+-----------+------------+
| Bill | Kerry | 0112 | 2017-10-01 |
+----------+---------+-----------+------------+
| Bill | Kerry | 0112 | 2017-10-02 |
+----------+---------+-----------+------------+
| Bill | Kerry | 0112 | 2017-10-03 |
+----------+---------+-----------+------------+
所以今天（2017-10-03）的结果将是......
+----------+---------+-----------+-------------+
| Forename | Surname | EMP_Num | Days Worked |
+----------+---------+-----------+-------------+
| John | Kerry | 0111 | 2 |
+----------+---------+-----------+-------------+
| Bill | Kerry | 0112 | 3 |
+----------+---------+-----------+-------------+
或2017-09-30的结果将是
+----------+---------+-----------+-------------+
| Forename | Surname | EMP_Num | Days Worked |
+----------+---------+-----------+-------------+
| John | Kerry | 0111 | 3 |
+----------+---------+-----------+-------------+
| Bill | Kerry | 0112 | 0 |
+----------+---------+-----------+-------------+
任何想法？
我正在运行SQL 2008所以没有领先或滞后我害怕。