MySQL從一個表中選擇數據，其中條件在其他表中

Question

我的SQL很生疏，我必須解決一個問題。我有三個表中的數據，如下所示。在table1和table2列中，username都是唯一的！

我需要列出max（year）= 2016（表3中）且必須是type = 0（來自table2）的所有用戶（來自table1）的地址。 根據示例中的數據，結果應爲：地址3

任何想法如何使用單個SQL命令執行此操作？我可以（並且我已經完成了）寫一個腳本，但它應該是一個（複雜的）SQL命令！

我試過連接，內部連接等，但作爲偶爾的SQL用戶，我的知識是有限的，至少可以說。

table1    table2   table3   
---------|-------- --------|---- --------|----- 
username |address username|type username| year 
---------|-------- --------|---- --------|----- 
user1 |address1 user1 | 1 user1 | 2015 
user2 |address2 user2 | 1 user1 | 2016 
user3 |address3 user3 | 0 user1 | 2017 
user4 |address4 user4 | 0 user2 | 2015 
            user2 | 2016 
            user3 | 2015 
            user3 | 2016 
            user4 | 2014 
            user4 | 2015 

Answer 1

select table1.address 
from table1 
    inner join table2 on table2.username = table1.username 
    inner join 
       (select username, max(date) maxDate 
       from table3 
       group by username) t3 on t3.username = table1.username 
where table2.type = 0 
     and t3.maxDate = 2016; 

或

select table1.address 
from table1 
    inner join table2 on table2.username = table1.username 
    inner join 
       (select username, max(date) maxDate 
       from table3 
       group by username 
       having max(date) = 2016) t3 on t3.username = table1.username 
where table2.type = 0; 

Answer 2

你可以試試這個，隊友：

SELECT 
-- I need to list addresses of all users (from table1) 
    t1.username, t1.address 
FROM 
    table1 t1 
    INNER JOIN table2 t2 ON t2.username = t1.username 
    INNER JOIN table3 t3 ON t3.username = t2.username 
-- and also must be of type=0 (from table2) 
WHERE t2.type = 0 
-- that have max(year)=2016 
HAVING MAX(t3.year) = 2016;