Sql oracle 分組依據和條件

Question

我有這些數據：

year code points
-------------
2017  M    1
2018  L    3
2019  L    5

我需要2019年的總分，取2019年之前與2019年代碼匹配的所有代碼

所以結果應該是：

y     c  p
----------
2019  L  8

我有一個 oracle 數據庫，不知道該怎么做（使用“連接方式”？）

輕松測試請求：

WITH test AS (
SELECT 2017 y, 'M' code, 1 point FROM DUAL
UNION
SELECT 2018 y, 'L' code, 3 point FROM DUAL
UNION 
SELECT 2019 y, 'L' code, 5 point FROM DUAL
)
SELECT * FROM test

Answer 1

您可以按如下方式進行self join以達到所需的結果：

SQL> WITH test AS (
  2  SELECT 2017 y, 'M' code, 1 point FROM DUAL
  3  UNION
  4  SELECT 2018 y, 'L' code, 3 point FROM DUAL
  5  UNION
  6  SELECT 2019 y, 'L' code, 5 point FROM DUAL
  7  )
  8  SELECT
  9      T1.Y,
 10      T1.POINT + COALESCE(T2.POINT,0) AS POINTS
 11  FROM
 12      TEST T1
 13      LEFT JOIN TEST T2 ON T1.CODE = T2.CODE
 14                           AND T1.Y > T2.Y
 15  WHERE T1.Y = '2019'
 16  ;

         Y     POINTS
---------- ----------
      2019          8

SQL>

或者您可以使用如下analytical function ：

SQL> WITH test AS (
  2  SELECT 2017 y, 'M' code, 1 point FROM DUAL
  3  UNION
  4  SELECT 2018 y, 'L' code, 3 point FROM DUAL
  5  UNION
  6  SELECT 2019 y, 'L' code, 5 point FROM DUAL
  7  )
  8  SELECT Y, POINTS FROM
  9  (SELECT
 10      T1.Y,
 11      SUM(T1.POINT) OVER (PARTITION BY CODE ORDER BY Y) AS POINTS
 12  FROM
 13      TEST T1)
 14  WHERE Y = '2019'
 15  ;

         Y     POINTS
---------- ----------
      2019          8

SQL>

Answer 2

我想我會去：

select sum(points)
from (select code, sum(points) as points
      from t
      where y <= 2019
      group by code
      having max(y) = 2019
     ) x;

這處理兩種邊緣情況：

• 如果在 2019 年之后有幾年，它就會起作用。
• 如果給定年份的代碼有多行，則它有效。