Oracle SQL数据透视查询

我的数据如下表所示：

MONTH VALUE

1     100
2     200
3     300
4     400
5     500
6     600

我想写一个SQL查询，结果如下：

MONTH_JAN MONTH_FEB MONTH_MAR MONTH_APR MONTH_MAY MONTH_JUN
100       200       300       400       500       600

Oracle 9i+支持： 您只列出了两列——类似这样的内容可能应该按年份分组

有ANSI PIVOT（和UNPIVOT）语法，但Oracle直到11g才支持它。在9i之前，您必须将CASE语句替换为Oracle特定的解码。

Oracle 11g及以上版本 从Oracle 11g开始，您现在可以使用运算符来实现该结果：

create table tq84_pivot (
  month number,
  value number
);

insert into tq84_pivot values(1, 100);
insert into tq84_pivot values(2, 200);
insert into tq84_pivot values(3, 300);
insert into tq84_pivot values(4, 400);
insert into tq84_pivot values(5, 500);
insert into tq84_pivot values(6, 600);
--
insert into tq84_pivot values(1, 400);
insert into tq84_pivot values(2, 350);
insert into tq84_pivot values(4, 150);

select 
  *
from
  tq84_pivot
pivot (
   sum (value) as sum_value for
     (month) in (1 as month_jan,
                 2 as month_feb,
                 3 as month_mar,
                 4 as month_apr,
                 5 as month_mai,
                 6 as month_jun,
                 7 as month_jul,
                 8 as month_aug,
                 9 as month_sep,
                10 as month_oct,
                11 as month_nov,
                12 as month_dec)
);

Oracle 11g+的动态轴心

Oracle的SQL中没有直接的动态数据透视方法，除非它返回

XML

类型结果

对于

非XML

结果，可以通过创建

SYS\u REFCURSOR

返回类型的函数来使用PL/SQL

• 带枢轴子句

  CREATE OR REPLACE FUNCTION Get_Month_Values RETURN SYS_REFCURSOR IS
     v_recordset SYS_REFCURSOR;
     v_sql       VARCHAR2(32767);
     v_cols      VARCHAR2(32767);
  BEGIN
     SELECT LISTAGG( ''''||month||''' AS "MONTH_'||TO_CHAR( TO_DATE(month,'mm') ,'MON')||'"' , ',' )
                    WITHIN GROUP ( ORDER BY month )
       INTO v_cols
       FROM tab;
  
     v_sql :='SELECT *
                FROM tab t
               PIVOT
               (
                MAX(value) FOR month IN ( '|| v_cols ||' )
               )';
  
     OPEN v_recordset FOR v_sql;
     DBMS_OUTPUT.PUT_LINE(v_sql);
     RETURN v_recordset;
  END;
  /
  

• 使用条件聚合

  CREATE OR REPLACE FUNCTION Get_Month_Values RETURN SYS_REFCURSOR IS
     v_recordset SYS_REFCURSOR;
     v_sql       VARCHAR2(32767);
     v_cols      VARCHAR2(32767);
  BEGIN
     SELECT LISTAGG('MAX( CASE WHEN month = '''||month||''' THEN '||value||' END ) AS "MONTH_'||TO_CHAR( TO_DATE(month,'mm') ,'MON')||'"' , ',' )
                    WITHIN GROUP ( ORDER BY month )                 
       INTO v_cols
       FROM tab;
  
     v_sql :='SELECT '|| v_cols ||' FROM tab';
  
     OPEN v_recordset FOR v_sql;
     DBMS_OUTPUT.PUT_LINE(v_sql);
     RETURN v_recordset;
  END;
  /
  

然后该函数可以作为

VAR rc REFCURSOR
EXEC :rc := Get_Month_Values;
PRINT rc

从SQL开发人员的命令行

VAR rc REFCURSOR
EXEC :rc := Get_Month_Values;
PRINT rc