java面試（一）：數據庫基礎

1、創建表
create table s(
	id number(100),
	name varchar2(100),
	.........
)
2、增
insert into s(id,name) values (seq.Nextval,'ss')                  //id爲序列
3、刪
delete from s where id = 1
4、改
update s set name = 'a' where id = 1
5、查
select * from s where id = 1
6、修改字段
alter table s modify name varchar2(200)
7、內連接
select * from u inner join s on u.id = s.id
8、左外連接
select * from u left join s on u.id = s.id
9、去重
select distinct name from s where id  = 1
10、排序
select * from s order by time desc        //desc從大到小，asc從小到大
11、oracle分頁
select * from (select rownum as rn,* from s where rownum<=5) where rn >=10
12、mysql分頁
select * from s limit 0,2      //從0+1個數據開始，取2個
13、分組
select name,max(age) as amax from s where id > 10 group by name having amax > 25
14、聚合函數
sum、max、min、count、avg