總結（永久）SQL表中的數據

Question

Geetings，Stackers。

我在SQL表中有大量的數據點，我想以一種讓人聯想到RRD的方式總結它們。

假設表如

ID | ENTITY_ID | SCORE_DATE | SCORE | SOME_OTHER_DATA 
----+-----------+------------+-------+----------------- 
    1 | A00000001 | 01/01/2010 | 100 | some data 
    2 | A00000002 | 01/01/2010 | 105 | more data 
    3 | A00000003 | 01/01/2010 | 104 | various text 
... | ......... | .......... | ..... | ... 
... | A00009999 | 01/01/2010 | 101 | 
... | A00000001 | 02/01/2010 | 104 | 
... | A00000002 | 02/01/2010 | 119 | 
... | A00000003 | 02/01/2010 | 119 | 
... | ......... | .......... | ..... | 
... | A00009999 | 02/01/2010 | 101 | arbitrary data 
... | ......... | .......... | ..... | ... 
... | A00000001 | 01/02/2010 | 104 | 
... | A00000002 | 01/02/2010 | 119 | 
... | A00000003 | 01/01/2010 | 119 | 

我想每一個實體記錄結束了，每個月：

ID | ENTITY_ID | SCORE_DATE | SCORE | 
----+-----------+------------+-------+ 
... | A00000001 | 01/01/2010 | 100 | 
... | A00000002 | 01/01/2010 | 105 | 
... | A00000003 | 01/01/2010 | 104 | 
... | A00000001 | 01/02/2010 | 100 | 
... | A00000002 | 01/02/2010 | 105 | 
... | A00000003 | 01/02/2010 | 104 | 

（我不關心SOME_OTHER_DATA - 我會挑選一些東西 - 可能是第一個或最後一個記錄）

定期做這些事情的簡單方法是什麼？這樣就可以總結出上個日曆月中的任何事情嗎？

目前我的計劃是怎麼樣的：

• 對於每個ENTITYID
  • 對於每個月
    • 查找特定的月份
    • 更新第一條記錄的所有記錄平均得分與上一步的結果
    • 刪除所有不是第一個的記錄

我無法想象的，雖然這樣做的一個非常簡潔的方式，不涉及大量的更新和迭代。

這可以在SQL存儲過程中完成，也可以合併到生成此數據的.Net應用程序中，因此該解決方案並不一定是「一個大的SQL腳本」，但可以是:)

（SQL-2005）

Answer 1

這給一試：

--I am using @table variables here, you will want to use your actual table in place of @YourTable and a #Temptable for @YourTable2, with a PK on ID 
SET NOCOUNT ON 
DECLARE @YourTable table (ID int,ENTITY_ID char(9),SCORE_DATE datetime,SCORE int ,SOME_OTHER_DATA varchar(100)) 
DECLARE @YourTable2 table (ID int) 
INSERT INTO @YourTable VALUES (1 , 'A00000001','01/01/2010',100,'some data') 
INSERT INTO @YourTable VALUES (2 , 'A00000002','01/01/2010',105,'more data') 
INSERT INTO @YourTable VALUES (3 , 'A00000003','01/01/2010',104,'various text') 
INSERT INTO @YourTable VALUES (4 , 'A00009999','01/01/2010',101,null) 
INSERT INTO @YourTable VALUES (5 , 'A00000001','02/01/2010',104,null) 
INSERT INTO @YourTable VALUES (6 , 'A00000002','02/01/2010',119,null) 
INSERT INTO @YourTable VALUES (7 , 'A00000003','02/01/2010',119,null) 
INSERT INTO @YourTable VALUES (8 , 'A00009999','02/01/2010',101,'arbitrary data') 
INSERT INTO @YourTable VALUES (9 , 'A00000001','01/02/2010',104,null) 
INSERT INTO @YourTable VALUES (10, 'A00000002','01/02/2010',119,null) 
INSERT INTO @YourTable VALUES (11, 'A00000003','01/01/2010',119,null) 
SET NOCOUNT OFF 

SELECT 'BEFORE',* FROM @YourTable ORDER BY ENTITY_ID,SCORE_DATE 

UPDATE y 
    SET SCORE=dt_a.AvgScore 
    OUTPUT INSERTED.ID --capture all updated rows 
     INTO @YourTable2 
    FROM @YourTable y 
     INNER JOIN (SELECT --get avg score for each ENTITY_ID per month 
         ENTITY_ID 
          ,AVG(SCORE) as AvgScore 
          , DATEADD(month,DATEDIFF(month,0,SCORE_DATE),0) AS MonthOf,DATEADD(month,1,DATEADD(month,DATEDIFF(month,0,SCORE_DATE),0)) AS MonthNext 
         FROM @YourTable 
         --group by 1st day of current month and 1st day of next month 
         --so an index can be used when joining derived table to UPDATE table 
         GROUP BY ENTITY_ID, DATEADD(month,DATEDIFF(month,0,SCORE_DATE),0),DATEADD(month,1,DATEADD(month,DATEDIFF(month,0,SCORE_DATE),0)) 
        ) dt_a ON y.ENTITY_ID=dt_a.ENTITY_ID AND y.SCORE_DATE>=dt_a.MonthOf AND y.SCORE_DATE<dt_a.MonthNext 
     INNER JOIN (SELECT--get first row for each ENTITY_ID per month 
         ID,ENTITY_ID,SCORE_DATE,SCORE 
         FROM (SELECT 
            ID,ENTITY_ID,SCORE_DATE,SCORE 
             ,ROW_NUMBER() OVER(PARTITION BY ENTITY_ID,DATEADD(month,DATEDIFF(month,0,SCORE_DATE),0) ORDER BY ENTITY_ID,SCORE_DATE) AS RowRank 
            FROM @YourTable 
          ) dt 
         WHERE dt.RowRank=1 
        ) dt_f ON y.ID=dt_f.ID 

DELETE @YourTable 
    WHERE ID NOT IN (SELECT ID FROM @YourTable2) 


SELECT 'AFTER ',* FROM @YourTable ORDER BY ENTITY_ID,SCORE_DATE 

OUTPUT：

 ID   ENTITY_ID SCORE_DATE    SCORE  SOME_OTHER_DATA 
------ ----------- --------- ----------------------- ----------- ---------------------------------------------------------------------------------------------------- 
BEFORE 1   A00000001 2010-01-01 00:00:00.000 100   some data 
BEFORE 9   A00000001 2010-01-02 00:00:00.000 104   NULL 
BEFORE 5   A00000001 2010-02-01 00:00:00.000 104   NULL 
BEFORE 2   A00000002 2010-01-01 00:00:00.000 105   more data 
BEFORE 10   A00000002 2010-01-02 00:00:00.000 119   NULL 
BEFORE 6   A00000002 2010-02-01 00:00:00.000 119   NULL 
BEFORE 3   A00000003 2010-01-01 00:00:00.000 104   various text 
BEFORE 11   A00000003 2010-01-01 00:00:00.000 119   NULL 
BEFORE 7   A00000003 2010-02-01 00:00:00.000 119   NULL 
BEFORE 4   A00009999 2010-01-01 00:00:00.000 101   NULL 
BEFORE 8   A00009999 2010-02-01 00:00:00.000 101   arbitrary data 

(11 row(s) affected) 

(8 row(s) affected) 

(3 row(s) affected) 

     ID   ENTITY_ID SCORE_DATE    SCORE  SOME_OTHER_DATA 
------ ----------- --------- ----------------------- ----------- ---------------------------------------------------------------------------------------------------- 
AFTER 1   A00000001 2010-01-01 00:00:00.000 102   some data 
AFTER 5   A00000001 2010-02-01 00:00:00.000 104   NULL 
AFTER 2   A00000002 2010-01-01 00:00:00.000 112   more data 
AFTER 6   A00000002 2010-02-01 00:00:00.000 119   NULL 
AFTER 3   A00000003 2010-01-01 00:00:00.000 111   various text 
AFTER 7   A00000003 2010-02-01 00:00:00.000 119   NULL 
AFTER 4   A00009999 2010-01-01 00:00:00.000 101   NULL 
AFTER 8   A00009999 2010-02-01 00:00:00.000 101   arbitrary data 

(8 row(s) affected) 

Answer 2

這會給你平均爲您的所有數據：

select ENTITY_ID, year(SCORE_DATE) as Year, month(SCORE_DATE) as Month, avg(SCORE) as Avg 
from MyTable 
group by ENTITY_ID, year(SCORE_DATE), month(SCORE_DATE) 

要限制對特定的月份，如去年二月，你可以這樣做：

select ENTITY_ID, year(SCORE_DATE) as Year, month(SCORE_DATE) as Month, avg(SCORE) as Avg 
from MyTable 
where year(SCORE_DATE) = 2010 and month(SCORE_DATE) = 2 
group by ENTITY_ID, year(SCORE_DATE), month(SCORE_DATE) 

這個版本實際上會表現得更好，但參數是有點不太友好的處理：

select ENTITY_ID, year(SCORE_DATE) as Year, month(SCORE_DATE) as Month, avg(SCORE) as Avg 
from MyTable 
where SCORE_DATE >= '2/1/2010' and SCORE_DATE < '3/1/2010' 
group by ENTITY_ID, year(SCORE_DATE), month(SCORE_DATE) 

如果你想查詢總是返回最後一個月的數據，你可以這樣做：

select ENTITY_ID, year(SCORE_DATE) as Year, month(SCORE_DATE) as Month, avg(SCORE) as Avg 
from MyTable 
where year(SCORE_DATE) = year(dateadd(month, -1, getdate())) and month(dateadd(month, -1, getdate())) = 2 
group by ENTITY_ID, year(SCORE_DATE), month(SCORE_DATE) 

性能更好的版本：

select ENTITY_ID, year(SCORE_DATE) as Year, month(SCORE_DATE) as Month, avg(SCORE) as Avg 
from MyTable 
where SCORE_DATE >= dateadd(month, ((year(getdate()) - 1900) * 12) + month(getdate())-2, 0) 
    and SCORE_DATE < dateadd(month, ((year(getdate()) - 1900) * 12) + month(getdate())-1, 0) 
group by ENTITY_ID, year(SCORE_DATE), month(SCORE_DATE)