Oracle 截取指定长度的字符

去掉回车，换行符号，截取指定长度的字符

具体代码示例：

 --Function
 --去掉前后空格，截取字符，字符长度为P_Length
 create or replace function get_StringLen
 (
   P_Name IN VARCHAR2,
   P_Length IN int
 ) return varchar2 is
   v_Temp varchar2():='';
   v_Name varchar2():='';
   v_Len int:=;
   i int:=;
   k int:=;
 begin
   --去掉回车，换行符号
   select trim(translate(P_Name,chr()||chr(),',')) into v_Name from dual; 

   --取字串的长度
   select length(v_Name) into v_Len from dual; 

   --循环来取
   for i in reverse ..v_Len
   loop
     if (lengthb(substr(v_Name,-i,))<>length(substr(v_Name,-i,))) then
       k:=k+;
     else
       k:=k+;
     end if;
     if k<=P_Length then
       v_Temp:=v_Temp || substr(v_Name,-i,);
     end if;
     if k>=P_Length then
       CONTINUE;
     end if;
   end loop;

   return(v_Temp);

 end get_StringLen;

 --Test
 select get_StringLen('asdf',) from dual;--返回结果：'asdf'
 select get_StringLen('asd中国',) from dual;--返回结果：'asd中'
 select get_StringLen('asdfasdf',) from dual;--返回结果：'asdfa'