这样的sql语句怎么写?在线等待,高人指点......!!!!!!!

Question

SEND_DT1          SENDT_DT2         SENDT_DT2    VALID_POST2001-12-05 2001-12-05 2001-12-05 3
2001-12-05 2001-12-05 2001-12-05 2
2001-12-05 2001-12-05 2001-12-05 3
2001-12-05 2001-12-05 2001-12-05 3
2001-12-05 2001-12-05 2001-12-05 2
2001-12-05 2001-12-05 2001-12-05 1
2001-12-05 2001-12-05 2001-12-05 1
2005-11-01 2005-11-02 2005-11-03 1
2005-11-01 2005-11-02 2005-11-03 1
2005-11-01 2005-11-02 2005-11-03 1
2005-11-01 2005-11-02 2005-11-03 1
2005-11-01 2005-11-02 2005-11-03 3如果VALID_POST为1 则检索SEND_DT1 的值,如果VALID_POST为2 则检索SEND_DT2 的值,如果VALID_POST为3 则检索SEND_DT3 的值,并且要求检索出来的SEND_DT1或SEND_DT2或SEND_DT3不能为空,这个sql语句怎么写啊????
数据库是oralce

Answer 1

select decode(VALID_POST,1,SEND_DT1 ,2,SEND_DT2,3,SEND_DT3)
 from temp
where decode(VALID_POST,1,SEND_DT1 ,2,SEND_DT2,3,SEND_DT3) is not null;