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

文章是唯一的，但可以有多个作者（essay_writer_join）。此查询为我提供作者的文章，这些作者之间用逗号分隔。

问题是我需要再添加一个称为“ manager”的列，该列将显示作者的管理员。 管理员信息在WRITER_TABLE中，列名称为“ manager_name”。 essay_table具有作者的名字，姓氏和用户名。 棘手的部分是2位作家可以有2位不同的经理。 例如，对于文章“ 123”，作者是“ abc”和“ xyz”，而这些作者的管理者分别是“ lmo”和“ pqr”，那么记录应以以下格式表示

essay id      writer       manager
123          abc, xyz      lmo, pqr

在oracle 10g sql中这可能吗？ 我试图搜索类似的情况，但是找不到任何相关的解决方案。

Answer 1

您可以只在最里面的查询和中间的查询中包含manager_name ，然后也对该列重复聚合机制。 我将列和表别名更改为更加一致（并且还简化了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，文章的两位作者是否拥有同一位经理？ 那么您将看到重复的值：

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

那可能就是您想要看到的。

SQL Fiddle演示 。

如果确实要禁止重复管理器，则可以将聚合分为子查询。 我发现将这些添加到常用表表达式（又称为子查询重构）中时更容易阅读：

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，分配行号的每个子查询都使用其自己的内联视图来获取不同的值。 因此，对于获得的相同数据：

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

SQL小提琴 。