Oracle PL/SQL打印字符串的每个字母

Question

我需要自己打印出"Hello"这个词的字母,我写道:

Declare
c1 Number:=1;
c2 Varchar2(5);
begin
for c1 in 1..5
loop
select substr('Hello' , c1 , 1 ) into c2 from dual;
dbms_output.put_line(c2);
end loop;
end;

但是它会跳过前两个字母,然后输出

l
l
o

任何想法可能是什么问题？谢谢.

Answer 1

最好有循环结束限制 For i in 1..v_length这种方式Loop每次运行时都不必更改限制.

 Create or replace procedure print_string( IN_string IN varchar2 )
AS
v_length number(10);
v_out varchar2(20);
Begin
v_length := length(IN_string);
for i in 1..v_length
Loop
v_out  := substr(IN_string,i,1) ;
DBMS_OUTPUT.PUT_LINE(v_out);
End loop;
DBMS_OUTPUT.PUT_LINE('Text printed: ' || IN_string);
End;
 -- Procedure created.

BEGIN
print_string('Hello');
END;


-- Output:

H
e
l
l
o
Text printed: Hello

Statement processed.

Answer 2

它也可以在单个选择中完成：

SQL> select substr('hello', level, 1) Letter
  2  from dual
  3  connect by level <= length('hello');

L
-
h
e
l
l
o

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