【sql server 2000学习笔记4】索引，备份，恢复，分离， 附加， 实例，连接，规范化

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1索引
当表格使用主关键字(primarykeys)，默认情况下SQLServer会自动对包含该关键字的column(s)建立一个独有的cluster索引。

2备份<-->恢复
当数据库在使用时，是不可以备份的；

3分离<-->附加

4实例
每个实例运行一个对应一个SqlServer服务（sqlserver.exe）


use spjselect *from spj--查询至少供应了3项工程（包含3项）的供应商，--输出其供应商号和供应零件数量的总和，并按供应商号降序排列select sno, sum(qty)from spjgroup by sno having count(distinct(pno))>2order by sno descselect *from sgoselect *from spjgo--笛卡尔积select *from s, spjselect *from s cross join spj--自然连接select *from s, spjwhere s.sno = spj.snoselect *from s inner join spjon s.sno = spj.sno --外连接--左select *from s left outer join spjon s.sno = spj.sno --右select *from s right outer join spjon s.sno = spj.sno --全select *from s full outer join spjon s.sno = spj.sno --intersectioncreate database testintersectionuse testintersectioncreate table s1 (sno smallint primary key)create table s2 (sno smallint primary key)select *from s1go select *from s2godeclare @i smallintset @i = 1while(@i<=20)begininsert into s1 values(@i)set @i = @i+1end declare @i smallintset @i = 1while(@i<=20)begininsert into s2 values(@i)set @i = @i+2end select *from s1inner join select *from s2



规范化：
1nf->2nf:消除非主属性对码的部分函数依赖
2nf->3nf:消除非主属性对码的传递函数依赖
3nf->bcnf:消除主属性对码的部分和传递函数依赖