oracle中使用sql的动态列

我有以下表格示例。 Thera可以是无限的分支机构和客户。我需要对这些分支机构进行分组并计算其客户数量，然后用不同的列显示它。

BRANCHNAME  CUSTOMERNO
100         1001010
100         1001011
103         1001012
104         1001013
104         1001014
104         1001015
105         1001016
105         1001017
106         1001018

请注意，可以有无限的分支机构和客户，查询必须不仅在这种情况下有效。

在这种情况下，可接受的结果是：

100 103 104 105 106
 2   1   3   2   1

SQL 数据示例

    select '100' BranchName,'1001010' CustomerNo from dual   UNION ALL 
    select '100' BranchName,'1001011' CustomerNo from dual   UNION ALL 
    select '103' BranchName,'1001012' CustomerNo from dual   UNION ALL 
    select '104' BranchName,'1001013' CustomerNo from dual   UNION ALL 
    select '104' BranchName,'1001014' CustomerNo from dual   UNION ALL 
    select '104' BranchName,'1001015' CustomerNo from dual   UNION ALL 
    select '105' BranchName,'1001016' CustomerNo from dual   UNION ALL 
    select '105' BranchName,'1001017' CustomerNo from dual   UNION ALL 
    select '106' BranchName,'1001018' CustomerNo from dual   

我认为虽然相当复杂，但还是可以写一个返回变量结构的流水线表函数 http://asktom.oracle.com/pls/apex/f?p=100:11:0::::P11_QUESTION_ID:4843682300346852395#5421020800346627246。您的管道表函数将使用 Oracle Data Cartridge 接口和 AnyDataSet 类型的魔力在运行时返回动态结构。然后您可以在后续 SQL 语句中使用它，就像它是一个表一样，即

SELECT *
  FROM TABLE( your_pipelined_function( p_1, p_2 ));

更多讨论相同示例实现的参考资料

• 动态 SQL 透视 http://technology.amis.nl/2006/05/24/dynamic-sql-pivoting-stealing-antons-thunder/
• The 实现接口方法 http://docs.oracle.com/cd/E11882_01/appdev.112/e10765/pipe_paral_tbl.htm#ADDCI4701Oracle Data Cartridge 开发人员指南的部分

• Method4. https://github.com/method5/method4下载并安装开源PL/SQL代码后，以下是完整的实现：

  --Create sample table.
  create table branch_data as
  select '100' BranchName,'1001010' CustomerNo from dual   UNION ALL 
  select '100' BranchName,'1001011' CustomerNo from dual   UNION ALL 
  select '103' BranchName,'1001012' CustomerNo from dual   UNION ALL 
  select '104' BranchName,'1001013' CustomerNo from dual   UNION ALL 
  select '104' BranchName,'1001014' CustomerNo from dual   UNION ALL 
  select '104' BranchName,'1001015' CustomerNo from dual   UNION ALL 
  select '105' BranchName,'1001016' CustomerNo from dual   UNION ALL 
  select '105' BranchName,'1001017' CustomerNo from dual   UNION ALL 
  select '106' BranchName,'1001018' CustomerNo from dual;
  
  --Create a dynamic pivot in SQL.
  select *
  from table(method4.dynamic_query(
      q'[
          --Create a select statement
          select
              --The SELECT:
              'select'||chr(10)||
              --The column list:
              listagg(
                  replace(q'!sum(case when BranchName = '#BRANCH_NAME#' then 1 else 0 end) "#BRANCH_NAME#"!', '#BRANCH_NAME#', BranchName)
                  , ','||chr(10)) within group (order by BranchName)||chr(10)||
              --The FROM:
              'from branch_data' v_sql
          from
          (
              --Distinct BranchNames.
              select distinct BranchName
              from branch_data
          )
      ]'
  ));