如何聯接兩個表並映射三列

Question

2個表table1和表2； 要求是映射表2中表1中的兩列

SELECT , t2.people_names, t2.peoples_names
FROM ( table1 t1 JOIN table2 t2 ON t2.people_ids=t1.people1 )

如果我添加FROM語句和AND，以便映射列people2，則會收到錯誤消息。

    FROM (table1 t1 JOIN table2 t2 ON t2.people_ids=t1.people1 AND 
   t2.people_ids=t1.people2 )​

Answer 1

您必須兩次加入people_names表。

SELECT t1.people1, tnames1.peoples_names, t1.people2, tnames2.peoples_names
FROM table1 t1 JOIN table2 tnames1 ON tnames1.people_ids = t1.people1
               JOIN table2 tnames2 ON tnames2.people_ids = t1.people2