数据库笔试题(含参考答案)现在有个表:A(id ,name,regdate)B(id,groupid) C(id,name2)写出下面的SQL语句1.统计A表中每个月注册用户数2.统计A表中有姓名相同的用户数3.如果表A中有姓名相同的用户,把相同的查出,写入表C中4.A中ID有多个相同的数据,A中姓名相同的ID只保留注册时间最大的数据大家帮帮忙,写一下吧1select count(*),to_char(regdate,'yyyymm') from A group by to_char(regdate,'yyyymm');2select count(*) from (select name from A group by name having count(*) >1);3 insert into C(name2) select name from A group by name having count(*) >1;4delete from A E where e.regdate < (select max(regdate) from a X where E.id = X.id);------redate(格式为2007/02/12)日期自己转化一下SQL> select to_date('2007/02/12','yyyy/mm/dd') from dual;TO_DATE('2007/02/12','YYYY/MM/------------------------------2007-2-12
学生表 student s_id int s_name varchar2 课程表 class c_id int c_name varchar2 选课表 xuanke id int s_id int c_id int 查询出选了2门课以上的学生的信息 select * from student where s_id in ( select s_id from xuanke group by s_id having count(c_id) >2)
