MySQL - 在查詢中將用戶用戶名映射到用戶ID

Question

我已經完成了一些複雜的SQL查詢，但從未通過多個值連接兩個表，並且我不確定是否有可能。

我有以下兩個表：

 users 
     +-------+----------+ 
     | u_ID | username | 
     +-------+----------+ 
     | 1 | Pablo | 
     +-------+----------+ 
     | 2 | Mike | 
     +-------+----------+ 


     Messages 
     +-------+----------+---------+ 
     | m_ID | auhor_id | message | 
     +-------+----------+---------+ 
     | 1 |  2 | Heelo5 | 
     +-------+----------+---------+ 
     | 2 |  1 | he4532 | 
     +-------+----------+---------+ 
     | 3 |  2 | he4111 | 
     +-------+----------+---------+ 
     | 4 |  1 | he4538 | 
     +-------+----------+---------+ 

將我需要什麼SQL查詢來獲取這個表？

+-------+----------+---------+ 
    | m_ID | username | message | 
    +-------+----------+---------+ 
    | 1 | Mike | Heelo5 | 
    +-------+----------+---------+ 
    | 2 | Pablo | he4532 | 
    +-------+----------+---------+ 
    | 3 | Mike | he4111 | 
    +-------+----------+---------+ 
    | 4 | Pablo | he4538 | 
    +-------+----------+---------+ 

Answer 1

select m.m_ID, u.username, m.message 
from Messages m, users u 
where m. auhor_id = u.m_ID; 

大概要在WHERE子句指定消息記錄附加條件。正如我寫的那樣，所有消息記錄都顯示出來。

Answer 2

select m.m_ID, u.username, m.message 
from messages m inner join users u on u.u_ID = m.auhor_id 

Answer 3

select 
m.m_ID, 
u.username, 
m.message 
from 
users u 
inner join messages m on u.u_ID = m.author_id 
order by 
m.m_ID;