我有一些如下数据。
date metric value
2011-05-18 09:17:25 m1 10
2011-05-18 09:17:25 m2 10
2011-05-17 09:17:25 m1 30
2011-05-17 09:17:25 m2 40
2011-05-16 09:17:25 m1 50
2011-05-16 09:17:25 m2 60
2011-05-15 09:17:25 m1 40
2011-05-15 09:17:25 m2 30
lost of more...
我想将两天前的行合并到列中，如下所示。
date m1 m2 offsetdays offset_date m1 m2
2011-05-18 09:17:25 10 10 2 2011-05-16 09:17:25 50 60
2011-05-17 09:17:25 30 40 2 2011-05-15 09:17:25 40 30