PHP-消息收件箱系统

Question

I am developing a messaging inbox system. Users create message threads directed at another user. It will work as follows:

1. Message threads you receive appear in your inbox.
2. Message threads you create also appear in your inbox.
3. Message threads you delete are only deleted from your own inbox.

I have the following fields in my message_thread table:

• id
• from_user_id
• to_user_id
• subject
• deleted
• updated_at

I have managed to implement 1 and 2 using the following query:

SELECT * FROM message_thread mt
WHERE ((mt.from_user_id = 1 OR mt.to_user_id = 1) AND mt.deleted = 0)
ORDER BY mt.updated_at DESC

I am trying to figure out a way of implementing 3.

I assume new columns will need to be introduced ( from_user_deleted and to_user_deleted ). Is it possible to retrieve the correct resultset by extending the query or will this need to be done in the server side script (currently using PHP)?

EDIT: If user A deletes a thread and then user B sends a reply to that thread, it should re-appear in user A's inbox.

Answer 1

Try below code:

1.You can add new field as status

2.Status

    1 = from_user_deleted
    2 = to_user_deleted

Then Query

SELECT * FROM message_thread mt
WHERE ((mt.from_user_id = 1 OR mt.to_user_id = 1) AND mt.deleted = 0 AND mt.status<>2)
ORDER BY mt.updated_at DESC

Answer 2

In plain english:

Where ( The message is to you OR ( the message is from you AND the message is not deleted ) )

Answer 3

I have managed to solve this by adding a new table:

message_thread_status

• message_thread_id (FK)
• user_id (FK)
• deleted (default 0)

When a message_thread is created, it creates two entries in the message_thread_status table (one for each user in the message thread).

I then just need to find the record for the current user in the message_thread_status table and add in a condition to check for the value of deleted .

New query:

SELECT
     * FROM message_thread mt

LEFT OUTER JOIN
     message_thread_status mts ON mts.message_thread_id = mt.id

WHERE
    ((mt.from_user_id = 1 OR mt.to_user_id = 1)
    AND (mts.user_id = 1 AND mts.deleted = 0))

ORDER BY
    mt.updated_at DESC