我正在制作一个应用程序,用户可以在其中与其他用户聊天(1个,而不是组聊天)。我有一个MySQL表,该表存储了每个用户的所有消息,例如:
from_id to_id message time
abc123 def456 Hello 789
def456 abc123 What's up? 1234`
def456 abc123 How was last night? 2345
abc123 p0tat0 I missed the bus 3456
def456 p0tat0 I hate you :( 4567`
def456 another_user I hate Potato! 5678`
我如何从最新到最古老的abc123
获得最新消息,例如:
from_id to_id message time
abc123 p0tat0 I missed the bus 3456
def456 abc123 How was last night? 2345
time
如果很重要的话,消息表中始终处于上升顺序。
任何帮助将不胜感激。谢谢 ^。 ^
SELECT *,
'from' as direction
FROM messages WHERE from_username='admin' AND 'time' = ( SELECT MAX('time') FROM messages WHERE from_username='admin'
OR to_username='admin'
)
UNION ALL
SELECT *,
'to' as direction
FROM messages WHERE to_username='admin' AND 'time' = ( SELECT MAX('time') FROM messages WHERE
to_username='admin' OR
to_username='admin' )
尝试此
SELECT * FROM
messageTable
WHERE from_id='abc123'
AND `time` = ( SELECT MAX(`time`) FROM messageTable WHERE from_id='abc123' )
UNION ALL
SELECT * FROM
messageTable
WHERE to_id='abc123'
AND `time` = ( SELECT MAX(`time`) FROM messageTable WHERE to_id='abc123' )