具有多个 table 联接的 Oracle LISTAGG

Question

我正在使用 Oracle 18.c 我有一个查询，我在其中加入了三个表。效果很好。

select ae."PRIM_KEY", 
ae."EVENT_DATE",
ae."EVENT_NAME",
ac."FIRST_NAME" || ' ' || ac."LAST_NAME" "PRESENTER"
from    "AFF_EVENT_V" ae
      , "AFF_CONTACT" ac
      , "AFF_EVENT_PRESENTER" aep
where   aep."EVENT_FKEY" = ae."PRIM_KEY"
and     aep."CONTACT_FKEY" = ac."PRIM_KEY"
Order by event_date desc
;

查询产生如下结果：

PRIM_KEY	EVENT_DATE	EVENT_NAME	PRESENTER
641	26-APR-21	Event 99	George Washington
622	19-APR-21	Event 98	John Adams
541	25-JAN-21	Event 97	Thomas Jefferson
541	25-JAN-21	Event 97	James Madison
521	18-JAN-21	Event 96	James Monroe

在许多情况下，一个给定的事件有多个演示者。就像 541 的 Prim_Key。我想将给定事件的演示者分组在一起，以便结果如下所示：

PRIM_KEY	EVENT_DATE	EVENT_NAME	PRESENTER
641	26-APR-21	Event 99	George Washington
622	19-APR-21	Event 98	John Adams
541	25-JAN-21	Event 97	Thomas Jefferson, James Madison
521	18-JAN-21	Event 96	James Monroe

我尝试使用 LISTAGG 函数，但似乎无法正确使用。这是我试过的。

select ae."PRIM_KEY", 
ae."EVENT_DATE",
ae."EVENT_NAME",
LISTAGG(ac."FIRST_NAME" || ' ' || ac."LAST_NAME", ',') WITHIN GROUP (ORDER BY ac."LAST_NAME") as "PRESENTER"
from    "AFF_EVENT_V" ae
      , "AFF_CONTACT" ac
      , "AFF_EVENT_PRESENTER" aep
where   aep."EVENT_FKEY" = ae."PRIM_KEY"
and     aep."CONTACT_FKEY" = ac."PRIM_KEY"
Order by event_date desc
;

这会产生错误：ORA-00937: 不是单组函数。 连接多个表时如何使用 LISTAGG？

Answer 1

您必须添加一个 GROUP BY 子句

select ae."PRIM_KEY", 
ae."EVENT_DATE",
ae."EVENT_NAME",
LISTAGG(ac."FIRST_NAME" || ' ' || ac."LAST_NAME", ',') WITHIN GROUP (ORDER BY ac."LAST_NAME") as "PRESENTER"
from    "AFF_EVENT_V" ae
      , "AFF_CONTACT" ac
      , "AFF_EVENT_PRESENTER" aep
where   aep."EVENT_FKEY" = ae."PRIM_KEY"
and     aep."CONTACT_FKEY" = ac."PRIM_KEY"
Group BY 
ae."PRIM_KEY", 
ae."EVENT_DATE",
ae."EVENT_NAME"
Order by event_date desc
;

具有多个 table 联接的 Oracle LISTAGG

Oracle LISTAGG with multiple table joins

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