数据库面试题.doc

文档介绍：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


,把相同的查出,写入表C中
,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
1
select count(*),to_char(regdate,'yyyymm') from A group by to_char(regdate,'yyyymm');
2
select 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;
4
delete from A E where < (select max(regdate) from a X where = );
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redate(格式为