Question

如果表ticket包含主键id，表ticket_custom包含复合键ticket,name，我该如何加入id = ticket and name=X and id = ticket and name=Y。

表ticket_custom允许票证表扩展，它包含字段ticket,name,value。

我可以进行一次加入：

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。

Answer 1

如果我理解正确，这就是你要找的东西：

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

我这应该做的伎俩：

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

<强>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'

用复合键连接表两次

3 个答案: