Question

我需要连接5个表来获取必要的数据。

表1

id | number
1  | 1
2  | 5

表2

id | number | user_id
1  | 1      | 9
2  | 5      | 8

表3

id | name | 
8  | john | 
9  | jane |

表4

id | email
6  | johndoe@example.com

表5

id | table4_id | table3_id
1  | 6         | 8

表1是我的主表，我想将表3和表4中的名称和电子邮件分别添加到表1的select查询中，但是为了这样做，我需要使用表2和表5来连接因为表1和表3和表4之间没有直接的关系。我只知道如何连接3个表而不是5个表，对我来说如何处理这个问题似乎很困惑。

我按照here链接加入表1,2和3.但我不知道如何继续使用表4和表5.

这是我试过的查询：

SELECT table1.number, table2.number, table2.user_id, table3.id, table3.name,
table4.id, table4.email, table5.table4_id, table3_id
FROM table1
LEFT JOIN table2
    INNER JOIN table3
        //this query will work if I don't include this 2 inner joins
         INNER JOIN table4
            INNER JOIN table5
            ON table3.id = table5.table3_id
         ON table5.table4_id = table4.id
       //
      ON table2.user_id= table3.id
ON table2.number = table1.number;

错误:(如果包含表4和5的内部联接）

错误代码：1064。您的SQL语法有错误;检查手册，对应右边的MySQL服务器版本在table2.user_id = table3.id
附近使用的语法

Answer 1

正确的语法是select .. from .. join .. on .. join ..on ....

SELECT table1.number, table2.number, table2.user_id, table3.id, table3.name,  table4.id, table4.email, table5.table4_id, table3_id
FROM table1
LEFT JOIN table2 ON table2.number = table1.number
INNER JOIN table3 ON table2.user_id= table3.id
INNER JOIN table5 ON table3.id = table5.table3_id
INNER JOIN table4 ON table5.table4_id = table4.id

Answer 2

尝试使用以下结构。我是根据你提出的结构制作的

select t1.number, t2.number, t2.user_id, t3.id, t3.name,t4.id, t4.email, t5.t4_id, t3_id 
from table5 as t5 
join table4 as t4 on t5.table4_id = t4.id 
join table3 as t3 on t5.table3_id=t3.id 
join table2 as t2 on t2.user_id = t3.id 
join table1 as t1 on t2.number=t1.number

Answer 3

尝试以下代码。希望这会奏效。

Select t3.name,t4.email,t1.number,t2.user_id 
from table3 t3 JOIN table5 t5 ON t3.id=t5.table3_id 
JOIN table4 t4 ON t4.id=t5.table4_id
JOIN table2 t2 ON t2.user_id=t3.id
JOIN table1 t1 ON t1.number=t2.number;

如何在mysql中加入这5个表？

3 个答案: