本文介绍了用复合键联接表两次的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
给出具有主键id
的表ticket
和具有复合键ticket,name
的表ticket_custom
的方法,如何加入id = ticket and name=X and id = ticket and name=Y
.
Given the table ticket
with the primary key id
and the table ticket_custom
with the composite key ticket,name
how can I join for id = ticket and name=X and id = ticket and name=Y
.
表ticket_custom
允许对票证表进行扩展,它具有字段ticket,name,value
.
The table ticket_custom
allows the ticket table to be extended, it has the fields ticket,name,value
.
我可以进行单个加入:
SELECT id, summary, owner, ticket_custom.value
FROM ticket
INNER JOIN ticket_custom
ON id=ticket_custom.ticket AND ticket_custom.name='X'
我需要类似的东西:
SELECT id, summary, owner, ticket_custom.value, ticket_custom.value
FROM ticket
INNER JOIN ticket_custom
ON id=ticket_custom.ticket AND ticket_custom.name='X' AND ticket_custom.name='Y'
第一个ticket_custom.value
是id,x
的值,第二个是id,y
的值.
Where the first ticket_custom.value
is the value for id,x
and the second is for id,y
.
推荐答案
如果我正确理解,这就是您要寻找的东西:
If I understand correctly, this is what you are looking for:
SELECT id, summary, owner, c1.value, c2.value
FROM ticket t
INNER JOIN ticket_custom c1 ON t.id = c1.ticket AND c1.name = 'X'
INNER JOIN ticket_custom c2 ON t.id = c2.ticket AND c2.name = 'Y'
这篇关于用复合键联接表两次的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!