oracle的substr函数的用法 取得字符串中指定起始位置和长度的字符串 substr( string, start_position,
[
length
]
) 如: substr(
'
This is a test
'
,
6
,
2
) would
return
'
is
'
substr(
'
This is a test
'
,
6
) would
return
'
is a test
'
substr(
'
TechOnTheNet
'
,
-
3
,
3
) would
return
'
Net
'
substr(
'
TechOnTheNet
'
,
-
6
,
3
) would
return
'
The
'
select substr('Thisisatest', -4, 2) value from dual
length函数用法：length(dm)=4 取前4个字符