如何使用Oracle SQL爲每個月選擇一列的選擇最大值

Question

我想編制一份報告，顯示項目是否在一年的每個月中完成。有多少項目完成並不重要，只是項目是否完成。

with project_data as(
select '123' account, 'Started' status, to_date('01/01/2017','MM/DD/YY') 
sale_date from dual union all 
select '123' account, 'Complete' status, to_date('01/15/2017','MM/DD/YY') 
sale_date from dual union all 
select '123' account, 'Started' status, to_date('02/01/2017','MM/DD/YY') 
sale_date from dual union all 
select '123' account, 'Complete' status, to_date('04/12/2017','MM/DD/YY') 
sale_date from dual union all 
select '123' account, 'Complete' status, to_date('04/16/2017','MM/DD/YY') 
sale_date from dual) 

從這個例子中我想輸出到如：

Account Completed Month Year 
123  Yes  1  2017 
123  No  2  2017 
123  No  3  2017 
123  Yes  4  2017 

Answer 1

甲骨文設置：

CREATE TABLE table_name (account, status, sale_date) AS 
    select '123', 'Started', DATE '2017-01-01' from dual union all 
    select '123', 'Complete', DATE '2017-01-15' from dual union all 
    select '123', 'Started', DATE '2017-02-01' from dual union all 
    select '123', 'Complete', DATE '2017-04-12' from dual union all 
    select '123', 'Complete', DATE '2017-04-16' from dual union all 
    select '456', 'Complete', DATE '2017-03-28' from dual; 

查詢：

SELECT ACCOUNT, 
     MONTH, 
     CASE COUNT(CASE status WHEN 'Complete' THEN 1 END) 
     WHEN 0 
     THEN 'No' 
     ELSE 'Yes' 
     END AS Completed 
FROM (SELECT ADD_MONTHS(TRUNC(SYSDATE, 'YEAR'), LEVEL - 1) AS month 
     FROM DUAL 
     CONNECT BY ADD_MONTHS(TRUNC(SYSDATE, 'YEAR'), LEVEL - 1) <= SYSDATE) 
     LEFT OUTER JOIN 
     table_name t 
     PARTITION BY (t.account) 
     ON (month <= sale_date AND sale_date < ADD_MONTHS(month, 1)) 
GROUP BY Account, Month 
ORDER BY Account, Month; 

輸出：

ACC MONTH    COM 
--- ------------------- --- 
123 2017-01-01 00:00:00 Yes 
123 2017-02-01 00:00:00 No 
123 2017-03-01 00:00:00 No 
123 2017-04-01 00:00:00 Yes 
456 2017-01-01 00:00:00 No 
456 2017-02-01 00:00:00 No 
456 2017-03-01 00:00:00 Yes 
456 2017-04-01 00:00:00 No 

Answer 2

SELECT YEAR, 
     MONTH, 
     ACCOUNT, 
     CASE WHEN COMPLETED > 0 THEN 'YES' ELSE 'NO' END AS AT_LEAST_ONE_COMP 
    FROM ( SELECT EXTRACT (YEAR FROM SALE_DATE) AS YEAR, 
       EXTRACT (MONTH FROM SALE_DATE) AS MONTH, 
       ACCOUNT, 
       SUM (CASE WHEN STATUS = 'Complete' THEN 1 ELSE 0 END) 
        AS completed 
      FROM MY_TABLE 
     GROUP BY EXTRACT (YEAR FROM SALE_DATE), 
       EXTRACT (MONTH FROM SALE_DATE), 
       ACCOUNT)