1

我们可以使用“连接方式”从 oracle 中的分隔字符串生成行。喜欢：

SELECT Rn ,Regexp_Substr(data, '[^,]+', 1, LEVEL) Data
FROM (SELECT 1 Rn ,'id:a,val:b,desc:c' data FROM Dual) Idata
CONNECT BY Regexp_Substr(data, '[^,]+', 1, LEVEL) IS NOT NULL

我想将内部查询用作所有更多记录的联合。就像是：

SELECT Rn ,Regexp_Substr(data, '[^,]+', 1, LEVEL) Data
    FROM (SELECT 1 Rn ,'id:a,val:b,desc:c' data FROM Dual
      UNION ALL
      SELECT 2 Rn ,'id:a2,val:b2,desc:c2' data FROM Dual
      UNION ALL
      SELECT 3 Rn ,'id:a3,val:b3,desc:c3' data FROM Dual) Idata
    CONNECT BY Regexp_Substr(data, '[^,]+', 1, LEVEL) IS NOT NULL;

这样我就可以得到一个结果集，

RN  DATA
1   desc:c
1   id:a
1   val:b
2   desc:c2
2   id:a2
2   val:b2
3   desc:c3
3   id:a3
3   val:b3

但它不能正常工作，它来了：

RN  DATA
1   desc:c
1   desc:c
1   desc:c
1   desc:c
1   desc:c
1   desc:c
1   desc:c
1   desc:c
1   desc:c
1   id:a
1   val:b
1   val:b
1   val:b
2   desc:c2
2   desc:c2
2   desc:c2
2   desc:c2
2   desc:c2
2   desc:c2
2   desc:c2
2   desc:c2
:
:
:

应用 DISTINCT 不是目标。因为字符串可能不同，在这里拆分更大的字符串需要花费大量时间。我猜，在这个查询中，有些东西 LEVEL 生成是不合适的。可能需要使用 Rn 上的按设施分组。任何人都可以帮我写这个查询吗？提前谢谢。:)

4

1 回答 1

1

If you're using 11gR2 you can use RCTE:

with Idata as
(SELECT 1 Rn ,'id:a,val:b,desc:c' data FROM Dual
      UNION ALL
      SELECT 2 Rn ,'id:a2,val:b2,desc:c2' data FROM Dual
      UNION ALL
      SELECT 3 Rn ,'id:a3,val:b3,desc:c3' data FROM Dual),
rcte(rn, txt, token, i) as
(
  select rn, data, Regexp_Substr(data, '[^,]+', 1, 1), 2
  from Idata
  union all
  select rn, txt, Regexp_Substr(txt, '[^,]+', 1, i), i+1
  from rcte 
  where Regexp_Substr(txt, '[^,]+', 1, i) IS NOT null
  )
select rn, token
from rcte
order by rn;

If not, and adding DISTINCT is to heavy, then you can try a different approach such as using a pipelined function-

create or replace type t is object(token varchar2(100));
/
create or replace type t_tab as table of t;
/
create or replace function split_string(str varchar2, del in varchar2) return t_tab
  pipelined is

  token    varchar2(4000);
  str_t   varchar2(4000) ;
  v_del_i number;


begin

    str_t := str;

    while str_t is not null loop

      v_del_i := instr(str_t, del, 1, 1);

      if v_del_i = 0 then
        token  := str_t;
        str_t := '';
      else
        token  := substr(str_t, 1, v_del_i - 1);
        str_t := substr(str_t, v_del_i + 1);
      end if;

      pipe row(t(token));

    end loop;

 return;
end split_string;
/

Now the query could look like this:

select t.token, Idata.rn
from (SELECT 1 Rn ,'id:a,val:b,desc:c' data FROM Dual
      UNION ALL
      SELECT 2 Rn ,'id:a2,val:b2,desc:c2' data FROM Dual
      UNION ALL
      SELECT 3 Rn ,'id:a3,val:b3,desc:c3' data FROM Dual) Idata ,
      table(split_string(Idata.data, ',')) t

Here is a sqlfiddle demo

于 2013-07-02T08:15:42.863 回答