postgresql某个字段值按照指定规则排序

select id,serial_group_id,state
from ap_model 
order  by serial_group_id asc,
(
case 
when state=1 then 1
when state=2 then 2
when state=-1 then 3
when state=3 then 4
when state=0 then 5
else 99
end
)