截取字符串的函数：
select
'12345sda',
decode('12345sda','mm sp',null,nvl(substr('12345sda',0,instr('12345sda','-',1)-1),'12345sda')),
decode('12345sda','mm sp','12345sda',substr('12345sda', decode(instr('12345sda','-',1),0,null,instr('12345sda','-',1)) - length('12345sda'))),
'12345 - orgtest1',
decode('12345 - orgtest1','mm sp',null,nvl(substr('12345 - orgtest1',0,instr('12345 - orgtest1','-',1)-1),'12345 - orgtest1')),
decode('12345 - orgtest1','mm sp','12345 - orgtest1',substr('12345 - orgtest1', decode(instr('12345 - orgtest1','-',1),0,null,instr('12345 - orgtest1','-',1)) - length('12345 - orgtest1'))),
'mm sp',
decode('mm sp','mm sp',null,nvl(substr('mm sp',0,instr('mm sp','-',1)-1),'mm sp')),
decode('mm sp','mm sp','mm sp',substr('mm sp', decode(instr('mm sp','-',1),0,null,instr('mm sp','-',1)) - length('mm sp')))
from dual;