问题描述
Oracle 的PIVOT 子句的定义指定可以在 IN 子句中定义子查询.我想象的一个虚构的例子是这样的
Oracle's definition of the PIVOT clause specifies that there is a possibility to define a subquery in the IN clause. A fictional example of what I would imagine this to be is this
... PIVOT (AVG(salary) FOR (company) IN (SELECT DISTINCT company FROM companies))
然而，我得到一个 ORA-00936: Missing expression 错误.不幸的是，这个新的 PIVOT 子句的错误通常是相当神秘的.谁能给我一个很好的例子，说明如何在 PIVOT 子句的 IN 子句中使用子查询?
With that, however, I get an ORA-00936: Missing expression error. Unfortunately, errors from this new PIVOT clause are usually rather cryptic. Can anyone give me a good example of how a subquery can be used in the IN clause of the PIVOT clause?
推荐答案
显然，我懒得读到文档的最后......再往下，文档说明:
Apparently, I was too lazy to read to the end of the documentation... Further down, the documentation states:
子查询 子查询仅与 XML 关键字结合使用.当您指定子查询时，子查询找到的所有值都用于透视.[...]
subquery A subquery is used only in conjunction with the XML keyword. When you specify a subquery, all values found by the subquery are used for pivoting. [...]
这会起作用
PIVOT XML (AVG(salary) FOR (company) IN (SELECT DISTINCT company FROM companies))
查看完整文档
http://docs.oracle.com/cd/B28359_01/server.111/b28286/statements_10002.htm#CHDFAFIE
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