sql - 如何计算 PIVOT 查询中的所有级别？

Question

如何计算 PIVOT 查询中所有级别的计数？例如，这包括 ename 和 job，但如何计算所有工作级别的计数，而不仅仅是 CLERK、SALESMAN 和 MANAGER？

with pivot_data as (
  select ename, job
  from scott.emp
)
select * from pivot_data
pivot (count(*) for job in('CLERK', 'SALESMAN', 'MANAGER'));

Answer 1

IN要包含所有作业而不在 的子句中明确列出它们PIVOT，除了动态 sql 之外，您可以使用PIVOT XML和重写查询，如下所示：

-- sample of data
with t1(col) as(
  select 'CLERK'    from dual union all
  select 'SALESMAN' from dual union all
  select 'MANAGER'  from dual
)
select col_xml
  from t1
 pivot xml(
   count(*) for col in(select col from t1)
 )

XML 结果：

COL_XML                                                                         
--------------------------------------------------------------------------------
<PivotSet><item><column name = "COL">CLERK</column><column name = "COUNT(*)">1</
column></item><item><column name = "COL">MANAGER</column><column name = "COUNT(*
)">1</column></item><item><column name = "COL">SALESMAN</column><column name = "
COUNT(*)">1</column></item></PivotSet> 

但是，为了获得数据的友好表示，您必须显式提取值：

SQL> with t1(col) as(
  2    select 'CLERK'    from dual union all
  3    select 'SALESMAN' from dual union all
  4    select 'MANAGER'  from dual
  5  )
  6  select extractvalue(col_xml,'/PivotSet/item[1]/column[2]') col_1
  7       , extractvalue(col_xml,'/PivotSet/item[2]/column[2]') col_2
  8       , extractvalue(col_xml,'/PivotSet/item[3]/column[2]') col_3
  9    from ( select col_xml
 10             from t1
 11            pivot xml(
 12              count(*) for col in(select col from t1)
 13            )
 14         )
 15  ;

结果：

COL_1 COL_2 COL_3
-----------------
1     1     1

SQLFiddle 演示