【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...-优快云博客

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 spj select * 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 spj group by sno having count(distinct(pno))>2 order by sno desc select * from s go select * from spj go --笛卡尔积 select * from s, spj select * from s cross join spj --自然连接 select * from s, spj where s.sno = spj.sno select * from s inner join spj on s.sno = spj.sno --外连接 --左 select * from s left outer join spj on s.sno = spj.sno --右 select * from s right outer join spj on s.sno = spj.sno --全 select * from s full outer join spj on s.sno = spj.sno --intersection create database testintersection use testintersection create table s1 (sno smallint primary key) create table s2 (sno smallint primary key) select * from s1 go select * from s2 go declare @i smallint set @i = 1 while(@i<=20) begin insert into s1 values(@i) set @i = @i+1 end declare @i smallint set @i = 1 while(@i<=20) begin insert into s2 values(@i) set @i = @i+2 end select * from s1 inner 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