MySQL：在聯合表的子查詢上添加條件

Question

獲取該“用戶”所屬的所有房間，並列出每個房間的詳細信息，包括其

• id （ roomId ）
• 名稱 （ roomName ）
• 此會議室的總活躍用戶 （ activeUsers ）
• 房間中包含的總用戶數 （ totalUsers ）

提供以下表格結構：

Table:users
+---------+-------------------------+
| id(int) |  active(bool/tiny int)  |
+---------+-------------------------+

Table:rooms
+---------+----------------------+
| id(int) |  name(varchar(255))  |
+---------+----------------------+

Table:room_members
+-------------+---------------+
| userId(int) |  roomId(int)  |
+-------------+---------------+

到目前為止，我對SQL有點迷茫：

SELECT
    rooms.id,
    rooms.name,
    (SELECT SUM(users.active) FROM users WHERE room_members.roomId = rooms.id) activeUsers,
    (SELECT COUNT(users.id) FROM users WHERE room_members.roomId = rooms.id) totalUsers
FROM room_members
INNER JOIN rooms
ON room_members.roomId = rooms.id
INNER JOIN users
ON room_members.userId = users.id
WHERE room_members.userId = 1

根據這些數據：

我可以得出結論，我得到了錯誤的結果。

我想我需要你們的幫助。

Answer 1

您可以使用帶有分組依據的動態表（以及用戶和room_members之間的聯接）

SELECT
  rooms.id,
  rooms.name,
  t1.activeUsers,
  t1.totalUsers
FROM room_members 
INNER JOIN rooms  ON room_members.roomId = rooms.id
INNER JOIN users  ON room_members.userId = users.id
INNER JOIN  (  
                SELECT roomId, SUM(users.active)  as activeUsers, COUNT(users.id) as totalUsers
                FROM users 
                INNER JOIN room_members on users.id = room_members.userId
                group by roomId
            ) t1 on t1.roomID = rooms.id
WHERE room_members.userId = 1