添加摘要列

Question

我正在生成數據集UNION三個數據集。然後，我想在數據集的末尾添加一行summary，僅用於一列。

數據：

id uid type seen 
1 20 A  1 
2 20 B  1 
3 20 C  1 
4 6 A  1 
5 1 A  1 
6 3 A  0 
7 6 A  0 
8 1 B  0 

查詢：

SELECT * FROM 
(
    (SELECT 
      type, 
      GROUP_CONCAT(DISTINCT uid) AS users, 
      COUNT(type) AS typeCount, 
      MIN(seen) as seen 
    FROM `test2` 
    WHERE type = 'A' 
    GROUP BY type) 

    UNION 

    (SELECT 
      type, 
      GROUP_CONCAT(DISTINCT uid) AS users, 
      COUNT(type) AS typeCount, 
      MIN(seen) as seen 
    FROM `test2` 
    WHERE type = 'B' 
    GROUP BY type) 

    UNION 

    (SELECT 
      type, 
      GROUP_CONCAT(DISTINCT uid) AS users, 
      COUNT(type) AS typeCount, 
      MIN(seen) as seen 
    FROM `test2` 
    WHERE type = 'C' 
    GROUP BY type) 
) as result 

查詢結果：

id uid   type seen 
A 20,6,1,3 5  0 
B 20,1  2  0 
C 20   1  1 

個預期結果：

id  uid   type seen 
A  20,6,1,3 5  0 
B  20,1  2  0 
C  20   1  1 
total      2  -- counting `0` here 

PS：我知道查詢可以通過只使用GROUP BY被簡化，但它不是真實的情景，這是問題的只是最低限度的解釋。

Answer 1

您可以在query..just適用ROLLUP留下您的子查詢如知道對不對，然後對他們的申請GROUP BY

SELECT type, MIN(users) users, MIN(typeCount) typeCount, MIN(seen) seen, IF(seen=0,1,0) zero_seen FROM 
(

    -- previous sub query 

) as result 
GROUP BY type WITH ROLLUP 

編輯： ROLLUP只做總和或計算總計，做計數IF(seen=0,1,0) zero_seen加入計數0見過..