mysql - 使用复合键连接表两次

Question

给定ticket具有主键id的表ticket_custom和具有复合键的表，ticket,name我如何加入id = ticket and name=X and id = ticket and name=Y.

该表ticket_custom允许扩展工单表，它具有字段ticket,name,value。

我可以做一个单一的加入：

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'

其中第一个ticket_custom.value是 for 的值，id,x第二个是 for的值id,y。

Answer 1

如果我理解正确，这就是您要查找的内容：

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'

Answer 2

我这应该可以解决问题：

SELECT id, summary, owner, ticket_custom.value, ticket_custom.value
FROM ticket
INNER JOIN ticket_custom
ON ticket.id=ticket_custom.ticket
WHERE (ticket_custom.name='X' OR ticket_custom.name='Y')

Answer 3

也许

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' 
    OR id=ticket_custom.ticket AND ticket_custom.name='Y'