SQLServer2005 高校入门教学系列

SQL 语句基础

--查询学生中选修课程号 为1 的学生姓名

select sname 
from student
where exists(
    select *
    from sc    
    where student.sno = sc.sno
    and cno='1'
)

--查询选修了全部课程的学生姓名

select sname
from student
where exists(
    select *
    from course
    where  exists(
        select *
        from sc    
        where sc.cno = course.cno
                and sc.sno = student.sno
    )
)

-- 左值链接， 外链接


select student.sno,sname,ssex,sage,sdept,cno,grade
from student left outer join sc on (student.sno = sc.sno)


--建立唯一性索引

create unique index stu on student(sno asc,cno desc)


--having 代表着选择条件
select sno from sc group by sno 
having sno <> '200215121'

-- 修改数据表字段类型

alter table student alter column comment char(255)

alter table sc alter column grade smallint

-- 添加数据表列

alter table student add comment char(50)

alter table student add S_enterence datetime

alter table course add unique(cname)

-- 模糊精确条件

select *
from course
where cname like 'DB\_design' escape '\'

--查询课程名中含有DB_design的课程名


--建立存储过程

create procedure proc_insert_student
    @sno1 char(9),
    @sname char(20),
    @ssex char(2) = '男',
    @sage int,
    @sdept  char(20)
as 
begin
    insert into student(sno,sname,ssex,sage,sdept) 
    values(@sno1,@sname,@ssex,@sage,@sdept)
end

create proc proc_avgrade_sc
@sno char(9),
@savg int output  -- out
as 
begin
    select @savg = avg(grade)
    from sc where sno = @sno 
end


--执行存储过程
 exec proc_insert_student '2002015126','张新阳','男',19,'CS'
 exec proc_insert_student @sno1 = '2002015128',@sname = '尼阳',@sage = 22,@sdept = 'IS'


declare @avg int
 set @avg = 0
 exec proc_avgrade_sc '200215121',@avg output  

--输出参数必须是output 类型
--select @avg 平均成绩

--删除存储过程
drop prodc [procedure_name]