SQL常用實例（轉）
50个Sql语句，仅供学习！
Student(S#,Sname,Sage,S***) 学生表
Course(C#,Cname,T#) 课程表
SC(S#,C#,score) 成绩表
Teacher(T#,Tname) 教师表
问题：
1、查询“001”课程比“002”课程成绩高的所有学生的学号；
select a.S# from (select s#,score from SC where C#='001') a,(select s#,score
from SC where C#='002') b
where a.score>b.score and a.s#=b.s#;
2、查询平均成绩大于60分的同学的学号和平均成绩；
select S#,avg(score)
from sc
group by S# having avg(score) >60;
3、查询所有同学的学号、姓名、选课数、总成绩；
select Student.S#,Student.Sname,count(SC.C#),sum(score)
from Student left Outer join SC on Student.S#=SC.S#
group by Student.S#,Sname
4、查询姓“李”的老师的个数；
select count(distinct(Tname))
from Teacher
where Tname like '李%';
5、查询没学过“叶平”老师课的同学的学号、姓名；
select Student.S#,Student.Sname
from Student
where S# not in (select distinct( SC.S#) from SC,Course,Teacher where SC.C#=Course.C# and Teacher.T#=Course.T# and Teacher.Tname='叶平');
6、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名；
select Student.S#,Student.Sname from Student,SC where Student.S#=SC.S# and SC.C#='001'and exists( Select * from SC as SC_2 where SC_2.S#=SC.S# and SC_2.C#='002');
7、查询学过“叶平”老师所教的所有课的同学的学号、姓名；
select S#,Sname
from Student
where S# in (select S# from SC ,Course ,Teacher where SC.C#=Course.C# and Teacher.T#=Course.T# and Teacher.Tname='叶平' group by S# having count(SC.C#)=(select count(C#) from Course,Teacher where Teacher.T#=Course.T# and Tname='叶平'));
8、查询课程编号“002”的成绩比课程编号“001”�
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create PROCEDURE pagelist
@tablename nvarchar(50),
@fieldname nvarchar(50)='*',
@pagesize int output,--每页显示记录条数
@currentpage int output,--第几页
@orderid nvarchar(50),--主键排序
@sort int,--排序方式，1表示升序，0表示降序排列
......
--从Excel文件中,导入数据到SQL数据库中,很简单,直接用下面的语句:
/*===================================================================*/
--如果接受数据导入的表已经存在
insert into 表 select * from
OPENROWSET('MICROSOFT.JET.OLEDB.4.0'
,'Excel 5.0;HDR=YES;DATABASE=c:\test.xls',sheet1$)
--如 ......
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, ExtCtrls, Grids, DBGrids, DB, ADODB,comobj, OleServer,
ExcelXP;
type
TForm1 = class(TForm)
ADOConn: TADOConnection;
& ......
