Oracle 行转列 万能视图

之前发过一个帖子，叫行转列的通用过程，http://topic.csdn.net/u/20091019/11/67cd55a3-3f42-4db7-a3f8-91dd52a913cd.html能满足最基本的需求。但也有一些缺陷，现在对其进行完善
代码

1.使用视图SQL codecreate or replace procedure row_to_col(tabname in varchar2,
                                  group_col in varchar2,
                                  column_col in varchar2,
                                  value_col in varchar2,
                                  Aggregate_func in varchar2 default 'max',
                                  colorder in varchar2 default null,
                                  roworder in varchar2 default null,
                                  when_value_null in varchar2 default null,
                                  viewname in varchar2 default 'v_tmp')
Authid Current_User
as
  sqlstr varchar2(2000):='create or replace view '||viewname||' as select '||group_col||' ';
  c1 sys_refcursor;
  v1 varchar2(100);
begin
  open c1 for 'select distinct '||column_col||' from '||tabname||case when colorder is not null then ' order by '||colorder end;
  loop
    fetch c1 into v1;
    exit when c1%notfound;
    sqlstr:=sqlstr||chr(10)||','||case when when_value_null is not null then 'nvl(' end||
      Aggregate_func||'(decode(to_char('||column_col||'),'''||v1||''','||value_col||'))'||
      case when when_value_null is not null then chr(44) ||when_value_null||chr(41) end||'"'||v1||'"';
  end loop;
  close c1;
  sqlstr:=sqlstr||' from '||tabname||' group by '||group_col||case when roworder is not null then ' order by '||roworder end;
  execute immediate sqlstr;
end row_to_col;


这里修改了传入参数名，使其更容易理解。继续使用了创建视图这个方法，当然也可以改成用游标传出。
参数：
tabname 需要进行行转列操作的表名；
group_col 查询结果要按某列或某些列分组的字段名；
column_col 要从行转成列的字段；
value_col 需要聚合的值字段；
Aggregate_func 选用的聚合函数，可选，默认为max；
colorder 行转列后列的排序，可选；
roworder 行转列后记录的排序，可选；
when_value_null 若value_col字段的值聚合后为空，则转换成该值，可选；
viewname 创建的视图名称，可选，默认为v_tmp。

举例：
SQL code--测试数据
create table rowtocol_test as
select 2009 year,1 month,'部门1' dept,50000 expenditure from dual
union all select 2009,2,'部门1',20000 from dual
union all select 2009,2,'部门1',30000 from dual
union all select 2010,1,'部门1',35000 from dual
union all select 2009,2,'部门2',40000 from dual
union all select 2009,3,'部门2',25000 from dual
union all select 2010,2,'部门3',60000 from dual
union all select 2009,2,'部门3',15000 from dual
union all select 2009,2,'部门3',10000 from dual;

我现在想根据year和month分组，将部门转成列。
SQL codeSQL> select * from rowtocol_test;

      YEAR      MONTH DEPT  EXPENDITURE
---------- ---------- ----- -----------
      2009          1 部门1       50000
      2009          2 部门1       20000
      2009          2 部门1       30000
      2010          1 部门1       35000
      2009          2 部门2       40000
      2009          3 部门2       25000
      2010          2 部门3       60000
      2009          2 部门3       15000
      2009          2 部门3       10000

9 rows selected

SQL> execute row_to_col('rowtocol_test','year,month','dept','expenditure');

PL/SQL procedure successfully completed

SQL> select * from v_tmp;

      YEAR      MONTH        部门1        部门3        部门2
---------- ---------- ---------- ---------- ----------
      2009          1      50000           
      2010          1      35000           
      2009          3                            25000
      2009          2      30000      15000      40000
      2010          2                 60000

SQL>

这个结果可能不是我们想要的，重新调用过程，使用几个可选参数
SQL codeSQL> execute row_to_col('rowtocol_test','year,month','dept','expenditure',Aggregate_func => 'sum',colorder => 'dept',roworder => '1,2',when_value_null => '0');

PL/SQL procedure successfully completed

SQL> select * from v_tmp;

      YEAR      MONTH        部门1        部门2        部门3
---------- ---------- ---------- ---------- ----------
      2009          1      50000          0          0
      2009          2      50000      40000      25000
      2009          3          0      25000          0
      2010          1      35000          0          0
      2010          2          0          0      60000

SQL>

进行行转列的也可以是视图
SQL codeSQL> create view view_rowtocol as select * from rowtocol_test where year=2009;

View created

SQL> execute row_to_col('view_rowtocol','year,month','dept','expenditure',Aggregate_func => 'sum',colorder => 'dept',roworder => '1,2',when_value_null => '0');

PL/SQL procedure successfully completed

SQL> select * from v_tmp;

      YEAR      MONTH        部门1        部门2        部门3
---------- ---------- ---------- ---------- ----------
      2009          1      50000          0          0
      2009          2      50000      40000      25000
      2009          3          0      25000          0

SQL>

-----------------------------------------------------------
2.稍加修改，使用函数，返回游标。或利用过程里的传出参数SQL codecreate or replace function row_to_col_func(tabname in varchar2,
                                  group_col in varchar2,
                                  column_col in varchar2,
                                  value_col in varchar2,
                                  Aggregate_func in varchar2 default 'max',
                                  colorder in varchar2 default null,
                                  roworder in varchar2 default null,
                                  when_value_null in varchar2 default null
                                  )return sys_refcursor
Authid Current_User
as
  sqlstr varchar2(2000):='select '||group_col||' ';
  c1 sys_refcursor;
  v1 varchar2(100);
  cur sys_refcursor;
begin
  open c1 for 'select distinct '||column_col||' from '||tabname||case when colorder is not null then ' order by '||colorder end;
  loop
    fetch c1 into v1;
    exit when c1%notfound;
    sqlstr:=sqlstr||chr(10)||','||case when when_value_null is not null then 'nvl(' end||
      Aggregate_func||'(decode(to_char('||column_col||'),'''||v1||''','||value_col||'))'||
      case when when_value_null is not null then chr(44) ||when_value_null||chr(41) end||'"'||v1||'"';
  end loop;
  close c1;
  open cur for sqlstr||' from '||tabname||' group by '||group_col||case when roworder is not null then ' order by '||roworder end;
  return cur;
end row_to_col_func;

在pl/sql dev中可以在sql窗口执行，查看结果
SQL codeselect
row_to_col_func('rowtocol_test','year,month','dept','expenditure',Aggregate_func => 'sum',colorder => 'dept',roworder => '1,2',when_value_null => '0')
from dual;

ROW_TO_COL_FUNC('ROWTOCOL_TEST
<Cursor>

YEAR    MONTH    部门1    部门2    部门3
2009    1    50000    0        0
2009    2    50000    40000    25000
2009    3    0        25000    0
2010    1    35000    0        0
2010    2    0        0        60000