[英]A procedure to Reverse a String in PL/SQL
我刚开始学习 PL/SQL,但不确定如何创建过程。 逻辑似乎是正确的,但我认为第一行中有一些语法错误。 这是我的代码:-
CREATE OR REPLACE PROCEDURE ReverseOf(input IN varchar2(50)) IS
DECLARE
reverse varchar2(50);
BEGIN
FOR i in reverse 1..length(input) LOOP
reverse := reverse||''||substr(input, i, 1);
END LOOP;
dbms_output.put_line(reverse);
END;
/
两件事 - 您不应该在过程/函数的参数列表中指定数据类型大小,并且不需要DECLARE
关键字。 尝试这个:
CREATE OR REPLACE PROCEDURE ReverseOf(input IN varchar2) IS
rev varchar2(50):='';
BEGIN
FOR i in reverse 1..length(input) LOOP
rev := rev||substr(input, i, 1);
END LOOP;
dbms_output.put_line(rev);
END;
不用 PL/SQL 试试吧!
WITH
params AS
(SELECT 'supercalifragilisticexpialidocious' phrase FROM dual),
WordReverse (inpt, outpt) AS
(SELECT phrase inpt, CAST(NULL AS varchar2(4000)) outpt FROM params
UNION ALL
SELECT substr(inpt,2,LENGTH(inpt)-1), substr(inpt,1,1) || outpt
FROM wordReverse
WHERE LENGTH(inpt) > 0
)
SELECT phrase,outpt AS reversed FROM wordReverse, params
WHERE LENGTH(outpt) = LENGTH(phrase) ;
PHRASE REVERSED
---------------------------------- -----------------------------------
supercalifragilisticexpialidocious suoicodilaipxecitsiligarfilacrepus
引文: http : //rdbms-insight.com/wp/? p= 94
另一种解决方案反向字符串最小化循环计数
DECLARE
v_str VARCHAR2(100) DEFAULT 'MYSTRING';
v_len NUMBER;
v_left VARCHAR2(100);
v_right VARCHAR2(100);
BEGIN
v_len := LENGTH(v_str)/2;
FOR rec IN 1..v_len
LOOP
v_left := substr(v_str,rec,1) || v_left;
IF rec * 2 <= LENGTH(v_str) THEN
v_right := v_right || substr(v_str,-rec,1);
END IF;
END LOOP;
v_str := v_right || v_left;
dbms_output.put_line(v_str);
END;
set serveroutput on
declare
str1 varchar2(30);
len number(3);
str2 varchar2(30);
i number(3);
begin
str1:='&str1';
len:=length(str1);
for i in reverse 1..len
loop
str2:=str2 || substr(str1,i,1);
end loop;
dbms_output.put_line('Reverse string is: '||str2);
end;
/
create or replace procedure ap_reverse_number(input_no VARCHAR2) as
output_no VARCHAR2(100);
begin
for i in 1 .. length(input_no) loop
output_no := output_no || '' ||
substr(input_no, (length(input_no) - i + 1), 1);
end loop;
dbms_output.put_line('Input no. is :' || input_no);
dbms_output.put_line('Output no. is:' || output_no);
end;
这应该正确地完成工作。
试试这个单行语句来反转 sql 中的字符串
with a as (select 'brahma' k from dual)
select listagg(substr(k,length(k)-level+1,1),'') within group (order by 1) b from a connect by level<length(k)+1
declare
name varchar2(20):='&name';
rname varchar2(20);
begin
for i in reverse 1..length(name)
loop
rname:=rname||substr(name,i,1);
end loop;
display(rname);
end;
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