加入两个表并显示它来自哪里

Question

我有两张桌子：

ID, actor, description....
FK_ID, other_description...

我现在将加入这两个表，以便得到以下结果：

ID|actor|description|other_description
1, Bud Spencer, >MainDescription<, null
1, Bud Spencer, null, Other_Description1
1, Bud Spencer, null, Other_Description2
.....

如何撰写查询？

谢谢。

Answer 1

如果您需要同一行中的值您可以在id和fk_id

上使用左连接

select a.ID, a.actor, a.description, b.other_description
from table1 as a
left join table2 as b on a.ID = b.FK_ID

如果您需要同一列中的不同值，则可以使用union

select ID, actor, description
from table1 
union
select fk_ID, null, other_description
from table2

如果您需要所有值，可以使用union all

Answer 2

SELECT A.ID A.actor A.description B.other_description
FROM tableA A
INNER JOIN tableB B ON
A.ID = B.FK_ID

Answer 3

SELECT a.ID, a.actor, a.description, b.other_description
FROM DB1 a
JOIN DB2 b 
on a.ID=b.FK_ID