今天想写一个PLSQL的函数，需要实现递归，以前一直都没有在PLSQL里用过递归，上网查了一下发现PLSQL确实可以实现递归的，贴个网上的例子：
SQL> create or replace function get_char_one_by_one(v_str varchar2)
2 return varchar2 is
3 begin
4 if v_str is not null and length(v_str) > 1 then
5 return substr(v_str, 1, 1) || ' ' || get_char_one_by_one(substr(v_str, 2));
6 else
7 return v_str;
8 end if;
9 end;
10 /
Function created
SQL> select get_char_one_by_one('I am good boy') from dual;
GET_CHAR_ONE_BY_ONE('IAMGOODBO
-------------------------------------------
I a m g o o d b o y
自己随便写一个练练手，列出每个以','分开的字符部分：
SQL> create or replace function get_part(v_char in varchar2) return varchar2 is
2 v_temp integer;
3 v_insert_char varchar2(1000);
4 begin
5 v_temp := instr(v_char, ',', 1);
6 v_insert_char := substr(v_char, 1, v_temp - 1);
7 if v_temp > 0 then
8 dbms_output.put_line(v_insert_char);
9 return get_part(substr(v_char, v_temp + 1));
10 else
11 dbms_output.put_line(v_char);
12 return null;
13 end if;
14 end;
15 /
Function created
SQL> select get_part('42342fesh,43rfddfg,t35greg4,f43g54') from dual;
GET_PART('42342FESH,43RFDDFG,T
-----------------------------------------------
42342fesh
43rfddfg
t35greg4
f43g54
-The End-