下述查询语句该怎么写?

select a.city,(select value from table b on a.city=b.city and b.date=max(a.date)) from table a group by a.city

select * from table a where a.date = (select max(date) from table b where a.city = b.city)

1、select * from table a where a.date = (select max(date) from table b where a.city = b.city)

2、select tbname.* from tbname,(select city,max(date) m_date from tbname group by city) tbname2 where tbname.date = tbname2.m_date

两种写法都可以，但是在数据量较大时，第一种可能会用较长时间。