oracle -- 将 oracle 表中的多个逗号分隔值拆分为多行

Question

我在使用 oracle 拆分查询时遇到问题。

在 oracle 查询中使用 connect by 和正则表达式将逗号分隔的数据拆分为多行时，我得到了更多的重复行。例如，实际上我的表有 150 行，其中两行有逗号分隔的字符串，所以总的来说我只需要 155 行，但我得到 2000 行。如果我使用 distinct 它工作正常，但我不希望查询结果中有重复的行。

我尝试了以下查询，但是它在查询结果中生成了重复的行：

WITH CTE AS (SELECT 'a,b,c,d,e' temp,1 slno  FROM DUAL
              UNION 
              SELECT 'f,g',2 from dual
              UNION 
               SELECT 'h',3 FROM DUAL)

SELECT TRIM(REGEXP_SUBSTR( TEMP, '[^,]+', 1, LEVEL)) ,SLNO FROM CTE 
CONNECT BY LEVEL <= LENGTH(REGEXP_REPLACE(temp, '[^,]+')) + 1

编辑

上述选择查询只能拆分单个逗号分隔的字符串，但是，在具有多行的表上执行时会产生重复行。如何限制重复行？

Answer 1

添加一个独特的子句就可以了：

    WITH cte AS (
        SELECT 'a,b,c,d,e' temp, 1 slno FROM DUAL UNION 
        SELECT 'f,g',2 FROM DUAL UNION SELECT 'h',3 FROM DUAL
    ) SELECT UNIQUE(slno),REGEXP_SUBSTR(temp,'[^,]+', 1, LEVEL)temp FROM cte
    CONNECT BY LEVEL<=REGEXP_COUNT(temp, '[^,]+') ORDER BY slno;

Answer 2

我终于想出了这个答案

WITH CTE AS (SELECT 'a,b,c,d,e' temp, 1 slno FROM DUAL
              UNION
              SELECT 'f,g' temp, 2 slno FROM DUAL
              UNION
              SELECT 'h' temp, 3 slno FROM DUAL)
SELECT TRIM(REGEXP_SUBSTR(temp, '[^,]+', 1, level)), slno
FROM CTE
CONNECT BY level <= REGEXP_COUNT(temp, '[^,]+')
    AND PRIOR slno = slno
    AND PRIOR DBMS_RANDOM.VALUE IS NOT NULL

Answer 3

接受的答案使用了不合适的条件DBMS_RANDOM.VALUE IS NOT NULL。它只是防止循环循环，但是会出现一个直截了当的问题：dbms_random.VALUE 如何以及何时可以为 null？ 从逻辑上讲，它永远不会是 NULL。 p>

更合适的解决方案是使用sys.odciNumberList并防止循环循环。

例如，

设置

SQL> CREATE TABLE t (
  2    ID          NUMBER GENERATED ALWAYS AS IDENTITY,
  3    text        VARCHAR2(100)
  4  );

Table created.

SQL>
SQL> INSERT INTO t (text) VALUES ('word1, word2, word3');

1 row created.

SQL> INSERT INTO t (text) VALUES ('word4, word5, word6');

1 row created.

SQL> INSERT INTO t (text) VALUES ('word7, word8, word9');

1 row created.

SQL> COMMIT;

Commit complete.

SQL>
SQL> SELECT * FROM t;

        ID TEXT
---------- ----------------------------------------------
         1 word1, word2, word3
         2 word4, word5, word6
         3 word7, word8, word9

SQL>

必填查询：

SQL> SELECT t.id,
  2         trim(regexp_substr(t.text, '[^,]+', 1, lines.column_value)) text
  3  FROM t,
  4    TABLE (CAST (MULTISET
  5    (SELECT LEVEL FROM dual CONNECT BY LEVEL <= regexp_count(t.text, ',')+1)
  6                 AS sys.odciNumberList
  7                )
  8          ) lines
  9  ORDER BY id
 10  /

        ID TEXT
---------- --------------------------------------------------
         1 word1
         1 word2
         1 word3
         2 word4
         2 word5
         2 word6
         3 word7
         3 word8
         3 word9

9 rows selected.

使用XMLTABLE 的替代解决方案：

SQL> SELECT id,
  2         trim(COLUMN_VALUE) text
  3  FROM t,
  4    xmltable(('"'
  5    || REPLACE(text, ',', '","')
  6    || '"'))
  7  /

        ID TEXT
---------- ------------------------
         1 word1
         1 word2
         1 word3
         2 word4
         2 word5
         2 word6
         3 word7
         3 word8
         3 word9

9 rows selected.

SQL>

有很多方法可以完成任务，例如MODEL 子句。更多示例见Split comma delimited strings in a table

Answer 4

不使用 connect by：

WITH CTE AS (SELECT 'a,b,c,d,e' temp,1 slno  FROM DUAL
      UNION 
      SELECT 'f,g',2 from dual
      UNION 
       SELECT 'h',3 FROM DUAL
)
,x as (
  select
  ','||temp||',' temp
  ,slno
  from CTE
)
,iter as (SELECT rownum AS pos
    FROM all_objects
)
select
SUBSTR(x.temp
  ,INSTR(x.temp, ',', 1, iter.pos) + 1
  ,INSTR(x.temp, ',', 1, iter.pos + 1)-INSTR(x.temp, ',', 1, iter.pos)-1
) temp
,x.slno
from x, iter
where iter.pos < = (LENGTH(x.temp) - LENGTH(REPLACE(x.temp, ','))) - 1;

Answer 5

这样试试，

WITH CTE AS (SELECT 'a,b,c,d,e' temp,1 slno  FROM DUAL
              UNION 
              SELECT 'f,g',2 from dual
              UNION 
              SELECT 'h',3 FROM DUAL)
     SELECT regexp_substr (temp, '[^,]+', 1, rn)temp, slno
     FROM   cte
     CROSS JOIN 
     (
          SELECT ROWNUM rn
          FROM  (SELECT MAX (LENGTH (regexp_replace (temp, '[^,]+'))) + 1 max_l
                 from cte
                 )
          connect by level <= max_l
         )
     WHERE regexp_substr (temp, '[^,]+', 1, rn) IS NOT NULL
     order by temp;

Answer 6

可以使用下面的查询来转换行中的逗号分隔值

 SELECT trim(x.column_value.extract('e/text()')) COLUMNS
 from t t, table (xmlsequence(xmltype('<e><e>' || replace(valuestring,':','</e><e>')||  
 '</e></e>').extract('e/e'))) x   );