SQL除以ID並分組

Question

我在下面有以下查詢。 我試圖提取具有特定條件的記錄數，然后除以cstmr_id分組的記錄總數。 但是我遇到一個錯誤。 任何幫助，將不勝感激。 另外，該語句是子查詢，是較大的select查詢的一部分。 我正在使用SQL Server 2005

得到“ /附近的語法錯誤”錯誤

聲明：

((SELECT count(*) FROM cstmr WHERE active=1 AND cstmr_type LIKE '%dtr%' 
GROUP BY cstmr_id) 
/  --division sign here. dividing top query by bottom
(SELECT count(*) FROM cstmr WHERE cstmr_type LIKE '%dtr%'
GROUP BY cstmr_id) ) As cstmr_rate

cstmr表中的樣本數據：

cstmr_id    cstmr_type    active
3423        dtr           1
1236        dtr           1
1842        dtr           1
8273        sys           2
9384        aod           1
3847        sys           2

樣本預期結果：

cstmr_id    cstmr_rate
3423        88.98
1236        25.21
1842        58.01

基本偽代碼

僅選擇類型為“ dtr”的活躍客戶，然后除以客戶總數。 然后顯示每個客戶的派生比率。 這是一個非常基本的方程式，並使用相同的表“ cstr”

Answer 1

;WITH x AS 
(
  SELECT cstmr_id, active, c = COUNT(*) 
   FROM dbo.cstmr WHERE cstmr_type LIKE '%dtr%'
   GROUP BY cstmr_id, active
), 
cr(cstmr_id, cstmr_rate) AS
(
  SELECT cstmr_id, 
   SUM(CASE active WHEN 1 THEN c ELSE 0 END)*1.0 / SUM(c) 
  FROM x GROUP BY cstmr_id
)
SELECT cr.cstmr_id, cr.cstmr_rate --, other columns
FROM cr
--INNER JOIN -- other tables from your larger query

Answer 2

看來您缺少外部SELECT ：

select -- You are missing this
(
    (SELECT cast(count(*) as decimal(10,2))
    FROM cstmr 
    WHERE active=1 AND cstmr_type LIKE '%dtr%' 
    GROUP BY cstmr_id) 
/  --division sign here. dividing top query by bottom
    (SELECT cast(count(*) as decimal(10,2))
    FROM cstmr 
    WHERE cstmr_type LIKE '%dtr%'
    GROUP BY cstmr_id) 
) As cstmr_rate

Answer 3

除了語法問題之外，還有其他更簡單的方法來表達您想要的內容：

select count(distinct case when active = 1 then cstmr_id end)*1.0 / count(distinct cstmr_id)
from cstmr
where cstmr_type like '%dtr%'

如果cstmr表中未重復cstmr_id，則可以將其進一步簡化為：

select sum(case when active = 1 then 1.0 else 0.0 end) / count(*)
from cstmr
where cstmr_type like '%dtr%'

甚至：

select avg(active*1.0)
from cstmr
where cstmr_type like '%dtr%'

請注意，我還將整數轉換為浮點數。 如您所寫，它產生的值是0或1，因為SQL Server對整數進行整數運算。

Answer 4

這可能不起作用，因為這兩個查詢返回的記錄多於一條。 SQL Server無法將結果集除以結果集。

嘗試使用聯接取而代之。

編輯

像這樣：

SELECT 
    c.cstmr_id,
    c1/c2 AS 'cstmr_rate'
FROM cstmr as c
JOIN (
    SELECT cstmr_id, count(*) AS 'c1'
    FROM cstmr 
    WHERE active=1 
    AND cstmr_type LIKE '%dtr%' 
    GROUP BY cstmr_id
    ) AS sub1 ON c.cstmr_id = sub1.cstmr_id
JOIN (
    SELECT cstmr_id, count(*) AS 'c2'
    FROM cstmr 
    WHERE cstmr_type LIKE '%dtr%'
    GROUP BY cstmr_id
    ) AS sub2 ON c.cstmr_id = sub2.cstmr_id

編輯2

假設active為1或0，這可能也會起作用：

SELECT
    cstmr_id,
    SUM(Active)/COUNT(*)  AS 'cstmr_rate'
FROM cstmr
GROUP BY cstmr_id