Question

100分求2道面试题目的答案，灰常感谢

请写出这4个的sql语句

请写出这道题的算法，
请写出正确的代码，满意后再追加100分，谢谢

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Answer 1

四个SQL语句如下：

select a.t_ysear, sum(b.ta_num) as '销售金额'
from t_sales a, t_sales b
where b.t_ysear<=a.t_ysear
group by a.t_ysear

select max(t.a, t.b)
from t
union
select max(t.b, t.c)
from t

select a.id, count(*) CCC
from t a, t b
where a.id=b.id
and ccc > 1
group by a.id

假设表结构为t_rec{sn, acc_id, balance, dt}
语句为：
select acc_id, date(dt) dd, min(balance)
from t_rec
group by dd, acc_id