ORACLE分析函数--使用listagg实现行列转换

listagg函数是在oracle11g中新引入的聚合函数，当然也可以作为分析函数来使用。该函数可以基于分组内特定列的排序，将测量列进行拼接合并。

示例：

在10g中，该函数不被支持

[sql] 
SQL> select prod_id, LISTAGG(cust_first_name||' '||cust_last_name,';') WITHIN GROUP (order by amount_sold) cust_name from sales, customers  
  2  where sales.cust_id = customers.cust_id and cust_gender = 'M'   
and cust_credit_limit = 15000 and prod_id between 15 and 18  
and channel_id =2 and time_id > to_date('01-06-01','YY-MM-DD')  
group by prod_id;  3    4    5    
select prod_id, LISTAGG(cust_first_name||' '||cust_last_name,';') WITHIN GROUP (order by amount_sold) cust_name from sales, customers  
                                                                         *

第 1 行出现错误:

ORA-00923: 未找到要求的 FROM 关键字

在11g中，运行结果如下：

[sql] 
SQL> l  
  1  select prod_id, LISTAGG(cust_first_name||' '||cust_last_name,';') WITHIN GROUP (order by amount_sold) cust_name from sales, customers  
  2  where sales.cust_id = customers.cust_id and cust_gender = 'M'  
  3  and cust_credit_limit = 15000 and prod_id between 15 and 18  
  4  and channel_id =2 and time_id > to_date('01-06-01','YY-MM-DD')  
  5* group by prod_id  
SQL> /  
  
   PROD_ID CUST_NAME  
---------- ----------------------------------------------------------------------------------------------------  
    15 Mason Murray;Helga Nickols;Roxanne Crocker;Glenn Wong;Roxanne Crocker;Franklin Hagan;Franklin Hagan;  
       Ransom Wiser;Reyburn Markman  
  
    16 Forrest Lindsey;Helga Nickols;Helga Nickols;Roxanne Crocker;Garrett Manson;Roxanne Crocker;Franklin  
       Hagan;Prane Oppy;Franklin Hagan;Bud Smyth;Reyburn Markman  
  
    17 Garrett Manson;Roxanne Crocker;Helga Nickols;Roxanne Crocker;Helga Nickols;Mason Murray;Ethan Jeffre  
       ys;Franklin Hagan;Prane Oppy;Royd Ricketts  
  
    18 Erik Ready;Garrett Manson;Forrest Lindsey;Franklin Hagan;Franklin Hagan;Reyburn Markman

当然，listagg也可以基于over()的分区。

示例：

[sql] 
SQL> l  
  1  select time_id,prod_id,min(amount_sold),listagg(min(amount_sold),';') within group (order by prod_id) over (partition by time_id) cust_list  
  2  from sales where time_id > to_date('20-DEC-01','DD-MON-YY','NLS_DATE_LANGUAGE = American') and prod_id between 120 and 125  
  3* group by prod_id,time_id  
SQL> /  
  
TIME_ID            PROD_ID MIN(AMOUNT_SOLD) CUST_LIST  
------------------- ---------- ---------------- ----------------------------------------------------------------------  
2001-12-21 00:00:00    120        51.36 51.36;10.81  
2001-12-21 00:00:00    121        10.81 51.36;10.81  
2001-12-22 00:00:00    120        51.36 51.36;10.81;20.23;56.12;17.79;15.67  
2001-12-22 00:00:00    121        10.81 51.36;10.81;20.23;56.12;17.79;15.67  
2001-12-22 00:00:00    122        20.23 51.36;10.81;20.23;56.12;17.79;15.67  
2001-12-22 00:00:00    123        56.12 51.36;10.81;20.23;56.12;17.79;15.67  
2001-12-22 00:00:00    124        17.79 51.36;10.81;20.23;56.12;17.79;15.67  
2001-12-22 00:00:00    125        15.67 51.36;10.81;20.23;56.12;17.79;15.67  
2001-12-23 00:00:00    120        51.36 51.36;10.49;20.23;57.86;17.79;15.67  
2001-12-23 00:00:00    121        10.49 51.36;10.49;20.23;57.86;17.79;15.67  
2001-12-23 00:00:00    122        20.23 51.36;10.49;20.23;57.86;17.79;15.67  
  
TIME_ID            PROD_ID MIN(AMOUNT_SOLD) CUST_LIST  
------------------- ---------- ---------------- ----------------------------------------------------------------------  
2001-12-23 00:00:00    123        57.86 51.36;10.49;20.23;57.86;17.79;15.67  
2001-12-23 00:00:00    124        17.79 51.36;10.49;20.23;57.86;17.79;15.67  
2001-12-23 00:00:00    125        15.67 51.36;10.49;20.23;57.86;17.79;15.67  
2001-12-24 00:00:00    120        51.36 51.36;10.49;20.23;56.12;17.79;15.67  
2001-12-24 00:00:00    121        10.49 51.36;10.49;20.23;56.12;17.79;15.67  
2001-12-24 00:00:00    122        20.23 51.36;10.49;20.23;56.12;17.79;15.67  
2001-12-24 00:00:00    123        56.12 51.36;10.49;20.23;56.12;17.79;15.67  
2001-12-24 00:00:00    124        17.79 51.36;10.49;20.23;56.12;17.79;15.67  
2001-12-24 00:00:00    125        15.67 51.36;10.49;20.23;56.12;17.79;15.67  
2001-12-25 00:00:00    120        51.36 51.36;10.81  
2001-12-25 00:00:00    121        10.81 51.36;10.81  
  
TIME_ID            PROD_ID MIN(AMOUNT_SOLD) CUST_LIST  
------------------- ---------- ---------------- ----------------------------------------------------------------------  
2001-12-26 00:00:00    123        57.86 57.86  
2001-12-27 00:00:00    120        51.36 51.36;10.49;20.23;56.12;17.79;15.67  
2001-12-27 00:00:00    121        10.49 51.36;10.49;20.23;56.12;17.79;15.67  
2001-12-27 00:00:00    122        20.23 51.36;10.49;20.23;56.12;17.79;15.67  
2001-12-27 00:00:00    123        56.12 51.36;10.49;20.23;56.12;17.79;15.67  
2001-12-27 00:00:00    124        17.79 51.36;10.49;20.23;56.12;17.79;15.67  
2001-12-27 00:00:00    125        15.67 51.36;10.49;20.23;56.12;17.79;15.67  
2001-12-28 00:00:00    120        51.36 51.36;10.49;56.12;17.79;15.67  
2001-12-28 00:00:00    121        10.49 51.36;10.49;56.12;17.79;15.67  
2001-12-28 00:00:00    123        56.12 51.36;10.49;56.12;17.79;15.67  
2001-12-28 00:00:00    124        17.79 51.36;10.49;56.12;17.79;15.67  
  
TIME_ID            PROD_ID MIN(AMOUNT_SOLD) CUST_LIST  
------------------- ---------- ---------------- ----------------------------------------------------------------------  
2001-12-28 00:00:00    125        15.67 51.36;10.49;56.12;17.79;15.67  
2001-12-29 00:00:00    122        20.23 20.23;56.12;17.79;15.67  
2001-12-29 00:00:00    123        56.12 20.23;56.12;17.79;15.67  
2001-12-29 00:00:00    124        17.79 20.23;56.12;17.79;15.67  
2001-12-29 00:00:00    125        15.67 20.23;56.12;17.79;15.67  
2001-12-30 00:00:00    120        51.36 51.36;10.49  
2001-12-30 00:00:00    121        10.49 51.36;10.49  
2001-12-31 00:00:00    121        10.81 10.81

已选择41行。