MySQL - 在查询中将用户用户名映射到用户ID

Question

我已经完成了一些复杂的SQL查询，但从未通过多个值连接两个表，并且我不确定是否有可能。

我有以下两个表：

 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 | 
     +-------+----------+---------+ 

将我需要什么SQL查询来获取这个表？

+-------+----------+---------+ 
    | 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子句指定消息记录附加条件。正如我写的那样，所有消息记录都显示出来。

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;