Oracle SQL 数据透视查询

Posted 2023-05-09

【中文标题】Oracle SQL 数据透视查询

【英文标题】：Oracle SQL pivot query

【发布时间】：2011-01-30 07:29:41

【问题描述】：

我的表格中有如下数据：

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

【参考方案1】：

Oracle 11g 及以上

从 Oracle 11g 开始，您现在可以使用 PIVOT 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)
);

【参考方案2】：

Oracle 9i+ 支持：

SELECT SUM(CASE WHEN t.month = 1 THEN t.value ELSE 0 END) AS JAN,
       SUM(CASE WHEN t.month = 2 THEN t.value ELSE 0 END) AS FEB,
       SUM(CASE WHEN t.month = 3 THEN t.value ELSE 0 END) AS MAR,
       SUM(CASE WHEN t.month = 4 THEN t.value ELSE 0 END) AS APR,
       SUM(CASE WHEN t.month = 5 THEN t.value ELSE 0 END) AS MAY,
       SUM(CASE WHEN t.month = 6 THEN t.value ELSE 0 END) AS JUN
  FROM YOUR_TABLE t

您只列出了两列——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 DECODE。

【参考方案3】：

Dynamic Pivot 适用于 Oracle 11g+

在 Oracle 的 SQL 中没有直接的动态透视方法，除非它返回 XML 类型的结果。

对于non-XML 结果PL/SQL 可以通过创建SYS_REFCURSOR 返回类型的函数来使用

带有PIVOT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;
/

然后函数可以调用为

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

来自 SQL Developer 的命令行

Demo