Oracle全角半角转换函数(to_multi_byte/to_single_byte)在varchar/clob中的使用案例

开始之前先上两个函数在官方得详细说明，因为之前开发函数之前没去官方看说明，直接百度看说明导致得坑，下面是官方文档得截图，官方明确说明这两个函数不支持
clob字段处理，但是我们可以通过隐式转换来实现,后面给出了本人写的对正常情况下varchar类型的支持以及相同功能下clob字段的实现方法：


测试数据如下：

------测试数据：
create table test_tab(id number,name varchar2(1000),loc clob);
insert into test_tab values(1,'','');
insert into test_tab values(2,'	　，．·','	　．，·');
insert into test_tab values(3,' '||chr(10)||chr(13),' '||chr(10)||chr(13));
insert into test_tab values(4,'sdf 东方闪电ｓｄｆ１２３123	　．·','sdf 东方闪电ｓｄｆ１２３123	　．·');
insert into test_tab values(5,'123','123');
insert into test_tab values(6,' 1 2 3',' 1 2 3');
insert into test_tab values(7,'1 2 3','1 2 3');
insert into test_tab values(8,'1 2 3ADSDSａｓｄｓＡＳＤＡＳ','1 2 3ASDａｓｄｓＡＳＤＡＳ');
insert into test_tab values(10,'	1 2 3ADSDSａｓｄｓＡＳＤＡＳ','	1 2 3ASDａｓｄｓＡＳＤＡＳ');
insert into test_tab values(11,'ｓｄｆ','ｓｄｆ');
commit;

具体函数如下：

----处理varchar类型数据
create or replace function trans_varchar(p_char varchar2) return varchar2 DETERMINISTIC is
  v_cache varchar2(4000);
  v_char varchar2(4000):=to_single_byte(p_char);
  cursor col is
    select regexp_substr(v_char, '[^[:digit:],^[:punct:],^[:cntrl:],^[:blank:]]', 1, level) as ch,
           regexp_substr(v_char, '[[:digit:]]', 1, level) as nu
      from dual
       connect by level <= case when length(p_char)>15 then 15 else length(p_char) end;
begin
  v_cache := '';
  for i in col loop
    case
      when asciistr(i.ch) between '\4E00' and '\9FA5' then
        v_cache := v_cache || i.ch;
        /* when  i.ch between 0 and 9 then 
        v_cache:=v_cache||i.ch;*/
      when i.ch between 'a' and 'z' then
        v_cache := v_cache || i.ch;
      when i.ch between 'A' and 'Z' then
        v_cache := v_cache || i.ch;
      else
        v_cache := v_cache || i.nu;
    end case;
  
  end loop;
  if v_cache is null then
    return null;
  else
    return rtrim(ltrim(rtrim(ltrim(rtrim(ltrim(trim(v_char),
                                               chr(9)),
                                         chr(9)),
                                   chr(10)),
                             chr(10)),
                       chr(13)),
                 chr(13));
  end if;
end trans_varchar;
/
----处理clob字段：
create or replace function trans_clob(p_char clob) return clob DETERMINISTIC is
  v_cache varchar2(4000);
   v_char clob:=to_single_byte(dbms_lob.substr(p_char));
  cursor col is
   select regexp_substr(v_char, '[^[:digit:],^[:punct:],^[:cntrl:],^[:blank:]]', 1, level) as ch,
           regexp_substr(v_char, '[[:digit:]]', 1, level) as nu
      from dual
    connect by level <= 15;
begin
  v_cache := '';
  for i in col loop
    case
      when asciistr(i.ch) between '\4E00' and '\9FA5' then
        v_cache := v_cache || i.ch;
        /* when  i.ch between 0 and 9 then
        v_cache:=v_cache||i.ch;*/
      when i.ch between 'a' and 'z' then
        v_cache := v_cache || i.ch;
      when i.ch between 'A' and 'Z' then
        v_cache := v_cache || i.ch;
      else
        v_cache := v_cache || i.nu;
    end case;
  end loop;
  if v_cache is null then
    return null;
  else
    return rtrim(ltrim(rtrim(ltrim(rtrim(ltrim(trim(v_char),
                                               chr(9)),
                                         chr(9)),
                                   chr(10)),
                             chr(10)),
                       chr(13)),
                 chr(13));
  end if;
end trans_clob;
/