我有两个表ticket和attr.表ticket有ticked_id字段和其他几个字段.表attr有3个字段:
ticket_id - numeric
attr_type - numeric
attr_val - string
attr_type是固定的价值观.例如,它可以是1,2或3.
我需要进行查询,其结果将是4列:
ticket_id,attr_valfor attr_type=1,attr_valfor attr_type=2,attr_valforattr_type=3
如果没有为没有相应的值attr_type在attr表然后NULL值应在相应的列中显示.
例:
ticket
ticket_id: 1
ticket_id: 2
ticket_id: 3
attr
ticket_id: 1
attr_type: 1
attr_val: Foo
ticket_id: 1
attr_type: 2
attr_val: Bar
ticket_id: 1
attr_type: 3
attr_val: Egg
ticket_id: 2
attr_type: 2
attr_val: Spam …