1、string 需要截取的字符串 2、a 截取字符串的开始位置(注:当a等于0或1时,都是从第一位开始截取) 3、b 要截取的字符串的长度 select substr('helloworld','0','4') as 结果 from dual; hell select substr('helloworld','1','4') as 结果 from dual; hell select substr('helloworld','2','4') as 结果 from dual; ello
1、string 需要截取的字符串 2、a 可以理解为从第a个字符开始截取后面所有的字符串。 select substr('helloworld','0') as 结果 from dual; helloworld select substr('helloworld','1') as 结果 from dual; helloworld select substr('helloworld','2') as 结果 from dual; elloworld
oracle中0、1都从第一个开始
如果a为负数,则b失效,从后面开始数
select substr('helloworld','-1') as 结果 from dual; d select substr('helloworld','-1','4') as 结果 from dual; d 两者结果都为d
1.rtrim 右侧开始,包含’1253'中任意一个都删除
select rtrim('5151561651','1253') as 结果 from dual; 51515616
2.ltrim 左侧开始,包含’1253'中任意一个都删除
select ltrim('5151561651','1253') as 结果 from dual; 61651
3.trim 删除两侧空格
select trim(' 1253 ') as 结果 from dual; 1253
4.从两侧开始,与both一致
select trim('2'from '22342') as 结果 from dual; 34 select trim(both '2'from '22342') as 结果 from dual; 34
5.leading 从头部
select trim(leading '2'from '22342') as 结果 from dual; 342
6.trailing 从尾部
select trim(trailing '2'from '22342') as 结果 from dual; 342