ylbtech-SQL Server:SQL Server-数据库操作方法基础 |
数据库操作方法基础。
ylb: 数据库操作方法基础 返回顶部 |
----------试图操作(view)--------------------- --创建视图 create view titles_view as select title,type from titles --调用视图 select * from titles_view --删除视图 drop view titles_view --修改视图 alter view titles_view as select title,type,price from titles go--------对表(Table)的操作------------------ create table teacher ( number int primary key, name varchar(20) not null, sex char(2) check(sex=‘男‘ or sex=‘女‘), birthday datetime, job_title varchar(20), salary money, memo ntext, nicheng varchar(20) unique, height numeric(7,2) ) select * from teacher drop table student create table Student ( number int primary key, name varchar(20) not null, sex char(2) check(sex=‘男‘ or sex=‘女‘), teachernumber int foreign key references teacher(number) ) --在 Student 表 添加一个新列 alter table Student add birthday datetime,salary money --在 Student 表 删除一个已有的列 alter table Student drop column salary --在 Sutdent 表 修改一个列的约束 alter table Student alter column name varchar(20) insert Student(number,name,sex,teachernumber) values(0003,‘小小黑2‘,‘男‘,1) insert Student(number,name,sex,teachernumber) values(0004,‘小小黑4‘,‘男‘,1) --外键必须产生于主键 --在删除的时候,如果这表上的列在其他表有外键的话 --(如果插入的数据产生关联)必须先删外键数据之后,才可以删除这表的数据 ------ ------查询技术 use pubs go --查询书名表的所有列 select * from titles --查询书名表的书名编号、书名名称、单价、类型 select * from titles select title_id,title,price,type from titles --as 用法 取别名 select title_id as ‘书名编号‘,title as ‘书名名称‘,price as ‘单价‘,type as‘类型‘ from titles --oder by 排序 asc,desc --查询书名表的所有列 按价格排序(从大到小) asc select title,price from titles order by price select title,price from titles order by price asc --查询书名表的所有列 按价格排序(从小到大)desc select title,price from titles order by price desc ---where 条件 --查看书名编号为:BU1111的记录信息 select * from titles select * from titles where title_id=‘BU1111‘ --查看书的类型是"business"的所有信息 select * from titles where type=‘business‘ -- in 包含 -- not in 不包含 -- or 或者 -- and 且 --查看书的类型是"business,mod_cook"的所有信息 select title,type from titles where type=‘business‘ ortype=‘mod_cook‘ select title,type from titles where typein(‘business‘,‘mod_cook‘) --查看书的类型不是"business,mod_cook"的所有信息 select title,type from titles where type!=‘business‘ andtype!=‘mod_cook‘ select title,[type] from titles where type notin(‘busines‘,‘mod_cook‘) --一些函数应用min,max,sum,avg,count,count(*) select * from titles --不算price 等于null ----min 最小值 select min(price) from titles select price from titles where type=‘business‘ select min(price) from titles where type=‘business‘ -----max 最大值 select max(price) from titles ----- sum 总和 select sum(price) from titles -----avg 平均值 select avg(price) from titles -----count(*),count(列明) select count(*) as ‘总计‘ from titles select count(title_id) ‘总计‘ from titles -- like 像 select * from titles --查一下 title_id 中有‘BU‘的所有行数 -----‘%‘ 代表所有字符 select * from titles where title_id like ‘%BU%‘ -----‘_’ 代表一个字符 select * from titles where title_id like ‘__1%‘ --group by 分组 select type,count(*) ‘记录总数‘,min(price) ‘最小价格‘,max(price)‘最大价格‘,sum(price) ‘总价格‘,avg(price) ‘平均价格‘ from titles group bytype --比较运算符=,>,<,>=,<=,!= ----!= 不等于 select title,price from titles select title,price from titles where price>10 --any 任何一个,all 都 select title,price from titles where price >any(select price from titles wheretype=‘business‘) select price from titles where type=‘business‘ select min(price) from titles where type=‘business‘ select title,price from titles where price >all(select price from titles wheretype=‘business‘) select max(price) from titles --exists 存在 use master go -------对数据库(Database)的操作--------------- if exists(select * from sys.databases where name=‘db2‘) begin drop database db2 end go create database db2 go use db2 2011/2/17 ylb pm17:20
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时间: 2024-10-13 05:31:48