SQL笔试题 取code相同的，value最大的记录

id	code	value
1	a	1
2	a	3
3	a	3
4	b	3
5	b	4
6	b	5

取code相同的，value最大的记录，value相同时，取id值大的

select * from test t1
where not exists (select * from test t2 where t1.code = t2.code and t1.value < t2.value)
and not exists (select * from test t3 where t1.code = t3.code and t1.value = t3.value and t1.id < t3.id)