MY_ID,NAME1,DATE1,EXP
2,CHEN,2002-01-09,0
5,ZHANG,2002-09-08,0
6,WEI,2002-08-01,0
8,CHEN2,2003-04-02,0

想求出MY_ID之差写进EXP里:
NAME1,EXP
CHEN,TOP
ZHANG,3
WEI,1
CHEN2,2