Oracle:聚合方法在分组结果中连接未分组的列

Question

我有一个查询与几个聚合函数,然后几个分组列.我想从组中取出一个分组列,并对它具有的所有VARCHAR值执行某种聚合"连接".(理想情况下,在一个新的运输分离列表中).

这是我的查询,我注意到我想要这样做:

SELECT rownum, F.*
FROM (SELECT 
  c.logical_type "MerchantType",
  c.merchant_id "MerchantID",
  c.m_name "MerchantName",
  m.m_name "TransferredBy", /* <----- Make this aggregate */
  SUM(DECODE(b.ba_price,null,0,DECODE(b.BILL_SRVC_ID,'CREDITCHANGE',0,b.ba_price))) "TotalValue", 
  sum(DECODE(b.ba_price,null,0,DECODE(b.BILL_SRVC_ID,'CREDITCHANGE',b.ba_price,0))) "LimitChange", 
  SUM(DECODE(b.ba_status,'bdone',1,0)) "TxnCount",
  sum(to_number(decode(substr(b.ba_merchant_freetext,1,10),'Commission',substr(b.ba_merchant_freetext, 12,(instr(b.ba_merchant_freetext,';',1,1)-12))))) "Commission"
FROM bill_auth0 b,
  merchant0 m,
  merchant0 c
WHERE 
  b.srvc_prod_id = 'TRANSFER'
    AND b.ba_channel = 'WPSS'
    AND b.ba_status     IN ('bdone')
    AND b.merchant_id    = m.merchant_id
    AND b.customer_id    = c.merchant_id
    AND b.ba_timestamp BETWEEN to_date( '11/01/2009', 'MM/DD/YYYY' ) 
        AND to_date( '11/17/2009', 'MM/DD/YYYY' )+1
GROUP BY 
  c.logical_type,
  c.merchant_id,
  c.m_name,
  m.m_name /* <-- Remove from Grouped By */
ORDER BY c.logical_type, c.merchant_id, m.m_name) F;

所以基本上我希望能够得到一个结果,其中"TransferredBy"看起来像:Merchant1
Merchant2
Merchant3

如果有3个单独的m.m_name匹配到此Group Row.

Answer 1

这是一篇关于不同字符串聚合技术的好文章.

我可以添加另一种方法(基于XML):

select rtrim(
         extract(
           sys_xmlagg(
             xmlelement("X",ename||', ')
           ),
           '/ROWSET/X/text()'
         ).getstringval(),
         ', '
       )
  from emp;

在11g第2版中,我们终于拥有了内置的LISTAGG功能.