集結SQL結果，兩個表，然後彙總結果

Question

使用MSSQL

我有用戶表，和產品表它們認購。這些訂閱是免費（F）或付費（P）。我已經加入了這些表格，使用case語句將F/P值轉換爲數字，然後通過用戶ID彙總這些值，想法是任何只有免費賬戶的人都會有0的總和，至少有一個付費帳戶價值1或更高。我用下面的遠獲得這樣的：

SELECT t1.user_id, SUM(
    CASE 
     WHEN t2.free_paid = 'P' 
      THEN 1 
     ELSE 0 
    END) as highest 
FROM users t1 INNER JOIN accounts t2 
    ON t1.user_id = t2.user_id 
WHERE t2.account = 'A' 
GROUP BY t1.user_id 
ORDER BY t1.user_id 

這將產生類似的結果：

755 2 
1259 2 
2031 1 
3888 0 

這意味着所有的，但3888至少有一個支付賬戶。

但是現在我想簡單地添加這些數據來獲得我們的兩個值，一個是至少有一個付費賬戶的用戶數（例如3個），另一個是隻有免費賬戶的用戶數例）。

我試過聲明兩個變量，例如： @free和@paid，並使用case語句將這些值包裝到子查詢中，然後將其作爲子查詢添加到這些值中，但無法運行。

任何想法？

Answer 1

重新使用查詢從這個問題您可以創建一個CTE（或子查詢），並彙總結果：

;WITH CTE_UserAccounts AS (
    SELECT t1.user_id, SUM(
     CASE 
      WHEN t2.free_paid = 'P' 
       THEN 1 
      ELSE 0 
     END) as highest 
    FROM users t1 INNER JOIN accounts t2 
     ON t1.user_id = t2.user_id 
    WHERE t2.account = 'A' 
    GROUP BY t1.user_id 
) 
SELECT 
    COUNT(CASE WHEN highest > 0 THEN 1 END) AS [Paid], 
    COUNT(CASE WHEN highest = 0 THEN 1 END) AS [Free] 
FROM 
    CTE_UserAccounts; 

Answer 2

SELECT 
COUNT(DISTINCT CASE WHEN t2.free_paid = 'P' THEN t1.user_id END) as atleast_one_paid, 
COUNT(DISTINCT CASE WHEN t2.free_paid <> 'P' THEN t1.user_id END) as onlyfree 
FROM users t1 
INNER JOIN accounts t2 ON t1.user_id = t2.user_id 
WHERE t2.account = 'A' 

Answer 3

你可以只環繞你的原始查詢和概括起來

SELECT SUM (case when highest > 0 THEN 1 else 0 END) as UsersWithPaidAccount, 
SUM (case when highest = 0 THEN 1 else 0 END) as UsersWithOnlyFreeAccount 
FROM (SELECT t1.user_id, SUM(
    CASE 
     WHEN t2.free_paid = 'P' 
      THEN 1 
     ELSE 0 
    END) as highest 
FROM users t1 INNER JOIN accounts t2 
    ON t1.user_id = t2.user_id 
WHERE t2.account = 'A' 
GROUP BY t1.user_id) 
as DerivedTable