MySQL查詢將兩個表連接在一起，並獲得組合數據的一行

Question

我有一個模型很差的數據庫，並且有兩個表（groupowner和groupmembers）具有幾乎相同的數據。我想創建一個視圖，將它們組合起來並按用戶分組。

用下面的查詢......

SELECT 'group' AS resourceType, gm.gid AS resource_id, gm.personid AS account_id, false AS isManager, true AS isMember 
FROM data.groupmembers gm 
    UNION 
SELECT 'group' AS resourceType, gn.gid AS resource_id, gn.owner AS account_id, true AS isManager, false AS isMember 
FROM data.groupowner gn 
    ORDER BY resource_id ASC, account_id ASC; 

...我得到的是這樣的：

resourceType | resource_id | account_id | isManager | isMember 
------------ | ----------- | ---------- | --------- | -------- 
group  | 105   | 506  | 1   | 0 
group  | 105   | 506  | 0   | 1 
etc... 

..when我想是這樣（這兩個表合併，或一個或另一個）：

resourceType | resource_id | account_id | isManager | isMember 
------------ | ----------- | ---------- | --------- | -------- 
group  | 105   | 506  | 1   | 1 
etc... 

有什麼辦法可以用MySQL查詢來實現這個嗎？

Answer 1

我想你想要一個join而不是union all。假設所有的業主成員，這應該工作和是「視圖」兼容MySQL中：

SELECT 'group' AS resourceType, gm.gid AS resource_id, gm.personid AS account_id, 
     (gn.personid is not null) AS isManager, true AS isMember 
FROM data.groupmembers gm LEFT JOIN 
    data.groupowner gn 
    ON gm.gid = gn.gid and 
     gm.personid = gn.personid; 

另一種方法是使用相關子查詢：

select gm.*, 
     (exists (select 1 
       from data.groupowner gn 
       where gm.gid = gn.gid and gm.personid = gn.personid 
     ) as IsManager 
from data.groupmembers; 

如果業主成員，我米不知道爲什麼你需要「isMember」列。

編輯：

如果業主不成員，那麼你獲得視圖兼容邏輯是一個挑戰。但是，這應該工作：

SELECT 'group' AS resourceType, gm.gid AS resource_id, gm.personid AS account_id, 
     (gn.personid is not null) AS isManager, true AS isMember 
FROM data.groupmembers gm LEFT JOIN 
    data.groupowner gn 
    ON gm.gid = gn.gid and 
     gm.personid = gn.personid 
UNION ALL 
SELECT 'group', gn.gid, gn.personid, 
     true, false 
FROM data.groupowner gn 
WHERE NOT EXISTS (SELECT 1 
        FROM data.groupmembers 
        WHERE gm.gid = gn.gid and gm.personid = gn.personid 
       ); 

Answer 2

嘗試在IsManager的和isMember使用下面的查詢慾望輸出

SELECT resourceType, resource_id, account_id, sum(isManager), sum(isMember) from 
(SELECT 'group' AS resourceType, gm.gid AS resource_id, gm.personid AS account_id, 0 AS isManager, 1 AS isMember 
FROM data.groupmembers gm 
    UNION 
SELECT 'group' AS resourceType, gn.gid AS resource_id, gn.owner AS account_id, 1 AS isManager, 0 AS isMember 
FROM data.groupowner gn 
    ORDER BY resource_id ASC, account_id ASC) temp 
group by resource_id, account_id;