50条常用sql语句
Student(S#,Sname,Sage,Ssex) 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“”课程比“”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“”并且也学过编号“”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“”的成绩比课程编号“&rdqu
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String keyword = request.getParameter("keyword");
String timeRange = request.getParameter("timeRange");
String type = request.getParameter("type");
StringBuffer sql = new StringBuffer();
sql.append("use webstation_leadall s ......
关键字: oracle & sql server
数据类型比较
类型名称
Oracle
SQLServer
比较
字符数据类型 CHAR CHAR 都是固定长度字符资料但oracle里面最大度为2kb，SQLServer里面最大长度为8kb
变长字符数据类型 VARCHAR2 VARCHAR Oracle里面最大长度为4kb，SQLServer里面最大长度为8kb
根据字符集而定的固定长度字� ......
-->Title:Generating test data
-->Author:wufeng4552
-->Date :2009-09-25 09:56:07
if object_id('tb')is not null drop table tb
go
create table tb(ID int,name text)
insert tb select 1,'test'
go
--方法1
select sql_variant_property(ID,'BaseType') from tb
--方法2
select object_name(ID)� ......
create function dbo.F_Get_No
(
@No varchar(100)
)
RETURNS bigint
AS
BEGIN
WHILE PATINDEX('%[^0-9]%',@No)>0
BEGIN
SET @No=STUFF(@No,PATINDEX('%[^0-9]%',@No),1,'') --删掉一个非数字的字符，循环结束，剩余的为数字部分
END
RETURN CONVERT(bigint,@No ......
列出TableA中有的而TableB中没有, 以及B中有而A中没有的记录：
其中两个表的结构相同，选择的Key可以多个
Select Key from
( select * from TableA
Union select * from TableB
)
group by Key
having count(Key)=1
列出TableA中有的而TableB中没有的记录：
Select Key from
( (select * from TableA
Un ......
