Rtrim in oracle

Question

i'm using below query

select rtrim(ename,substr(ename,2,10))||'->'||ename from emp order by ename;

to get below output

A->ALLEN
A->AMITH
B->BlAKE
S->SMITH ...... etc

but i am getting output like

 ->ALLEN
A->AMITH
B->BlAKE
S->SMITH

Any suggetions please, am i missing any thing? . Why the letter "A" in first line was missing.

Answer 1

Why not use

select SUBSTR(ename,1,1))||'->'||ename from emp order by ename;

It will return the first letter of each name

Answer 2

SELECT SUBSTRING(ename,1,1) + '->' + ename FROM SAMPLE ORDER BY ename;

我已经在SQL Server中尝试了上述查询，并且其工作正常。