Postgresql where in 排序
2016-07-13意思就是写where id in (...)的时候按照in里面的顺序来排列结果：
select *
from comments
where id in (1,3,2,4)
order by position(id::text in '1,3,2,4')
意思就是写where id in (...)的时候按照in里面的顺序来排列结果：
select *
from comments
where id in (1,3,2,4)
order by position(id::text in '1,3,2,4')