用于创建逗号分隔记录的 Oracle SQL 10g 查询

Question

我正在编写用于创建 jasper 报告的 oracle 10g 查询。

这是查询-

SELECT     essay_id,
           LTRIM (
              MAX (SYS_CONNECT_BY_PATH (full_name, ','))
                 KEEP (DENSE_RANK LAST ORDER BY curr),
              ',')
              AS full_name
FROM       (SELECT essay_id,
                   full_name,
                   ROW_NUMBER () OVER (PARTITION BY essay_id ORDER BY full_name)
                      AS curr,
                     ROW_NUMBER ()
                        OVER (PARTITION BY essay_id ORDER BY full_name)
                   - 1
                      AS prev
            FROM   (SELECT a.id AS essay_id,
                           CASE NVL (firstname, 'NULL FIRSTNAME')
                              WHEN 'NULL FIRSTNAME' THEN username
                              ELSE (firstname || ' ' || lastname)
                           END
                              AS full_name
                    FROM   essay_table a
                           INNER JOIN essay_writer_join ej ON a.id = ej.essay_id
                           INNER JOIN writer_table u ON ej.user_id = u.id))
GROUP BY   essay_id
CONNECT BY prev = PRIOR curr AND essay_id = PRIOR essay_id
START WITH curr = 1

论文是唯一的，但可以有多个作者(essay_writer_join) 此查询为我提供了由逗号分隔的作者的论文。

问题是我需要再添加一个名为 "manager" 的列来显示作者的经理。经理信息在 WRITER_TABLE 中，列名 "manager_name"。 essay_table 包含作者的名字、姓氏和用户名。棘手的部分是 2 个作者可以有 2 个不同的经理。例如，对于论文'123'，作者是'abc'和'xyz'，这些作者的经理分别是'lmo'和'pqr'，那么记录应按以下格式表示

essay id      writer       manager
123          abc, xyz      lmo, pqr

这在 oracle 10g sql 中可行吗？我试图搜索类似的情况，但没有找到任何相关的解决方案。

Answer 1

您可以只在最内层查询和中间查询中包含 manager_name，然后也对该列重复聚合机制。我已将列和 table 别名更改为更加一致（并且我还简化了您的 case 表达式）：

SELECT     essay_id,
           LTRIM (
              MAX (SYS_CONNECT_BY_PATH (writer, ','))
                 KEEP (DENSE_RANK LAST ORDER BY curr),
              ',')
              AS writer,
           LTRIM (
              MAX (SYS_CONNECT_BY_PATH (manager, ','))
                 KEEP (DENSE_RANK LAST ORDER BY curr),
              ',')
              AS manager
FROM       (SELECT essay_id,
                   writer,
                   manager,
                   ROW_NUMBER () OVER (PARTITION BY essay_id ORDER BY writer)
                      AS curr,
                     ROW_NUMBER ()
                        OVER (PARTITION BY essay_id ORDER BY writer)
                   - 1
                      AS prev
            FROM   (SELECT et.id AS essay_id,
                           CASE WHEN wt.firstname IS NULL THEN wt.username
                              ELSE (wt.firstname || ' ' || wt.lastname)
                           END
                              AS writer,
                           wt.manager_name as manager
                    FROM   essay_table et
                           INNER JOIN essay_writer_join ej ON et.id = ej.essay_id
                           INNER JOIN writer_table wt ON ej.user_id = wt.id))
GROUP BY   essay_id
CONNECT BY prev = PRIOR curr AND essay_id = PRIOR essay_id
START WITH curr = 1;

  ESSAY_ID WRITER     MANAGER  
---------- ---------- ----------
       123 abc,xyz    lmo,pqr

我能看到的唯一真正的问题是一篇文章的两位作者是否有同一个经理；然后你会看到重复的值：

  ESSAY_ID WRITER     MANAGER  
---------- ---------- ----------
       123 abc,xyz    lmo,pqr   
       456 abc,def    lmo,lmo

不过这可能是您想要看到的。

SQL Fiddle demo.

如果您确实想抑制重复的管理器，您可以将聚合分离到子查询中。我发现将这些拉入常见的 table 表达式（a.k.a。子查询重构）更容易阅读：

WITH all_data AS (
  SELECT et.id AS essay_id,
         CASE WHEN wt.firstname IS NULL THEN wt.username
            ELSE (wt.firstname || ' ' || wt.lastname)
         END
            AS writer,
         wt.manager_name as manager
  FROM   essay_table et
  JOIN   essay_writer_join ej ON et.id = ej.essay_id
  JOIN   writer_table wt ON ej.user_id = wt.id
),
writers AS (
  SELECT essay_id,
         writer,
         ROW_NUMBER () OVER (PARTITION BY essay_id ORDER BY writer) AS rn
  FROM   (
    SELECT distinct essay_id, writer
    FROM   all_data
  )
),
managers AS (
  SELECT essay_id,
         manager,
         ROW_NUMBER () OVER (PARTITION BY essay_id ORDER BY manager) AS rn
  FROM   (
    SELECT distinct essay_id, manager
    FROM   all_data
  )
)
SELECT   DISTINCT ad.essay_id,
         (
           SELECT     LTRIM (MAX (SYS_CONNECT_BY_PATH (w.writer, ','))
                        KEEP (DENSE_RANK LAST ORDER BY w.rn), ',')
           FROM       writers w
           WHERE      w.essay_id = ad.essay_id
           CONNECT BY w.rn = PRIOR w.rn + 1 AND w.essay_id = PRIOR w.essay_id
           START WITH w.rn = 1
         ) AS writer,
         (
           SELECT     LTRIM (MAX (SYS_CONNECT_BY_PATH (m.manager, ','))
                        KEEP (DENSE_RANK LAST ORDER BY m.rn), ',')
           FROM       managers m
           WHERE      m.essay_id = ad.essay_id
           CONNECT BY m.rn = PRIOR m.rn + 1 AND m.essay_id = PRIOR m.essay_id
           START WITH m.rn = 1
         ) AS manager
FROM     all_data ad
ORDER BY ad.essay_id;

重要的一点是每个分配行号的子查询都使用它自己的内联视图来获取不同的值。因此，对于获取的相同数据：

  ESSAY_ID WRITER     MANAGER  
---------- ---------- ----------
       123 abc,xyz    lmo,pqr   
       456 abc,def    lmo

SQL Fiddle.

用于创建逗号分隔记录的 Oracle SQL 10g 查询

Oracle SQL 10g query for creating comma separated records

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