users
id: int // users has_many chat_users
chats
id: int // chats has_many chat_users
chat_users
id: int
chat_id: int (foreign key) // chat_users belongs_to chat
user_id: int (foreign key) // chat_users belongs_to user
該數據庫具有以下記錄:
users, id: 1
users, id: 2
users, id: 3
chats, id: 1 // <---------
chats, id: 2
chat_users, id: 1, chat_id: 1, user_id: 1 // <-------
chat_users, id: 2, chat_id: 1, user_id: 2 // <-------
chat_users, id: 3, chat_id: 2, user_id: 2
chat_users, id: 4, chat_id: 2, user_id: 3
鑑於我有2個user_ids 1
和2
,我將如何編寫一個查詢的聊天記錄表中找到一個聊天:
1)與USER_ID ==一個chat_user 1
AND
2)與USER_ID == 2
一個chat_user?
請下次提供樣本數據作爲DDL + DML並添加相關的rdbms標記。 –