php代码中,用SQL语句查询查询数据库里面的信息,并显示出来
$question
$sql=
"select
from
tableName
where
question='$question'
";
//tableName
是你数据库的名字
//
question
是你数据库的字段名字
//
$question
是你问题的答案
select from table
where rownum<(select count()+1 from table)
minus
select from table
where rownum<(select count() from table)
也可以简化为
select from table
minus
select from table
where rownum<(select count() from table)
效果是一样的
切记rownum是伪列 只能用<
dl_会飞的青蛙的答案是错误的,他给出的是降序排列后的第一条,仅在排序过的时候是正确的。如果这个表是不排序的呢?他的答案就是错的
顺便给你求第X行的通用SQL语句
select from table where rownum<X+1
minus
select from table where rownum<X
就是返回到数据库,这个看你用什么方式了。如果你用sql语句,那么就是建立数据库连接,然后发送插入的sql语句。执行。如果是adonet里面通过datatable添加的,那么需要调用dataadpterupdate方法。网上有的,搜索下。
数据库常用sql语句有哪些
SQL语句有哪些?SQL语句无论是种类还是数量都是繁多的,很多语句也是经常要用到的,下文我为大家分享的就是SQL的常用语句,仅供参考!
50个常用的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“001”课程比“002”课程成绩高的所有学生的学号;
select aS# from (select s#,score from SC where C#='001') a,(select s#,score
from SC where C#='002') b
where ascore>bscore and as#=bs#;
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 StudentS#,StudentSname,count(SCC#),sum(score)
from Student left Outer join SC on StudentS#=SCS#
group by StudentS#,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 StudentS#,StudentSname
from Student
where S# not in (select distinct( SCS#) from SC,Course,Teacher where SCC#=CourseC# and TeacherT#=CourseT# and TeacherTname='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 StudentS#,StudentSname from Student,SC where StudentS#=SCS# and SCC#='001'and exists( Select from SC as SC_2 where SC_2S#=SCS# and SC_2C#='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 SCC#=CourseC# and TeacherT#=CourseT# and TeacherTname='叶平' group by S# having count(SCC#)=(select count(C#) from Course,Teacher where TeacherT#=CourseT# and Tname='叶平'));
8、查询课程编号“002”的成绩比课程编号“001”课程低的所有同学的学号、姓名;
Select S#,Sname from (select StudentS#,StudentSname,score ,(select score from SC SC_2 where SC_2S#=StudentS# and SC_2C#='002') score2
from Student,SC where StudentS#=SCS# and C#='001') S_2 where score2 <score;
9、查询所有课程成绩小于60分的同学的学号、姓名;
select S#,Sname
from Student
where S# not in (select StudentS# from Student,SC where SS#=SCS# and score>60);
10、查询没有学全所有课的同学的学号、姓名;
select StudentS#,StudentSname
from Student,SC
where StudentS#=SCS# group by StudentS#,StudentSname having count(C#) <(select count(C#) from Course);
11、查询至少有一门课与学号为“1001”的同学所学相同的同学的学号和姓名;
select S#,Sname from Student,SC where StudentS#=SCS# and C# in select C# from SC where S#='1001';
12、查询至少学过学号为“001”同学所有一门课的其他同学学号和姓名;
select distinct SCS#,Sname
from Student,SC
where StudentS#=SCS# and C# in (select C# from SC where S#='001');
13、把“SC”表中“叶平”老师教的课的成绩都更改为此课程的平均成绩;
update SC set score=(select avg(SC_2score)
from SC SC_2
where SC_2C#=SCC# ) from Course,Teacher where CourseC#=SCC# and CourseT#=TeacherT# and TeacherTname='叶平');
14、查询和“1002”号的同学学习的课程完全相同的其他同学学号和姓名;
select S# from SC where C# in (select C# from SC where S#='1002')
group by S# having count()=(select count() from SC where S#='1002');
15、删除学习“叶平”老师课的SC表记录;
Delect SC
from course ,Teacher
where CourseC#=SCC# and CourseT#= TeacherT# and Tname='叶平';
16、向SC表中插入一些记录,这些记录要求符合以下条件:没有上过编号“003”课程的同学学号、2、
号课的平均成绩;
Insert SC select S#,'002',(Select avg(score)
from SC where C#='002') from Student where S# not in (Select S# from SC where C#='002');
17、按平均成绩从高到低显示所有学生的“数据库”、“企业管理”、“英语”三门的课程成绩,按如下形式显示: 学生ID,,数据库,企业管理,英语,有效课程数,有效平均分
SELECT S# as 学生ID
,(SELECT score FROM SC WHERE SCS#=tS# AND C#='004') AS 数据库
,(SELECT score FROM SC WHERE SCS#=tS# AND C#='001') AS 企业管理
,(SELECT score FROM SC WHERE SCS#=tS# AND C#='006') AS 英语
,COUNT() AS 有效课程数, AVG(tscore) AS 平均成绩
FROM SC AS t
GROUP BY S#
ORDER BY avg(tscore)
18、查询各科成绩最高和最低的分:以如下形式显示:课程ID,最高分,最低分
SELECT LC# As 课程ID,Lscore AS 最高分,Rscore AS 最低分
FROM SC L ,SC AS R
WHERE LC# = RC# and
Lscore = (SELECT MAX(ILscore)
FROM SC AS IL,Student AS IM
WHERE LC# = ILC# and IMS#=ILS#
GROUP BY ILC#)
AND
RScore = (SELECT MIN(IRscore)
FROM SC AS IR
WHERE RC# = IRC#
GROUP BY IRC#
);
19、按各科平均成绩从低到高和及格率的百分数从高到低顺序
SELECT tC# AS 课程号,max(courseCname)AS 课程名,isnull(AVG(score),0) AS 平均成绩
,100 SUM(CASE WHEN isnull(score,0)>=60 THEN 1 ELSE 0 END)/COUNT() AS 及格百分数
FROM SC T,Course
where tC#=courseC#
GROUP BY tC#
ORDER BY 100 SUM(CASE WHEN isnull(score,0)>=60 THEN 1 ELSE 0 END)/COUNT() DESC
20、查询如下课程平均成绩和及格率的百分数(用"1行"显示): 企业管理(001),马克思(002),OO&UML (003),数据库(004)
SELECT SUM(CASE WHEN C# ='001' THEN score ELSE 0 END)/SUM(CASE C# WHEN '001' THEN 1 ELSE 0 END) AS 企业管理平均分
,100 SUM(CASE WHEN C# = '001' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '001' THEN 1 ELSE 0 END) AS 企业管理及格百分数
,SUM(CASE WHEN C# = '002' THEN score ELSE 0 END)/SUM(CASE C# WHEN '002' THEN 1 ELSE 0 END) AS 马克思平均分
,100 SUM(CASE WHEN C# = '002' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '002' THEN 1 ELSE 0 END) AS 马克思及格百分数
,SUM(CASE WHEN C# = '003' THEN score ELSE 0 END)/SUM(CASE C# WHEN '003' THEN 1 ELSE 0 END) AS UML平均分
,100 SUM(CASE WHEN C# = '003' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '003' THEN 1 ELSE 0 END) AS UML及格百分数
,SUM(CASE WHEN C# = '004' THEN score ELSE 0 END)/SUM(CASE C# WHEN '004' THEN 1 ELSE 0 END) AS 数据库平均分
,100 SUM(CASE WHEN C# = '004' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = '004' THEN 1 ELSE 0 END) AS 数据库及格百分数
FROM SC
21、查询不同老师所教不同课程平均分从高到低显示
SELECT max(ZT#) AS 教师ID,MAX(ZTname) AS 教师姓名,CC# AS 课程ID,MAX(CCname) AS 课程名称,AVG(Score) AS 平均成绩
FROM SC AS T,Course AS C ,Teacher AS Z
where TC#=CC# and CT#=ZT#
GROUP BY CC#
ORDER BY AVG(Score) DESC
22、查询如下课程成绩第 3 名到第 6 名的学生成绩单:企业管理(001),马克思(002),UML (003),数据库(004)
[学生ID],[学生姓名],企业管理,马克思,UML,数据库,平均成绩
SELECT DISTINCT top 3
SCS# As 学生学号,
StudentSname AS 学生姓名 ,
T1score AS 企业管理,
T2score AS 马克思,
T3score AS UML,
T4score AS 数据库,
ISNULL(T1score,0) + ISNULL(T2score,0) + ISNULL(T3score,0) + ISNULL(T4score,0) as 总分
FROM Student,SC LEFT JOIN SC AS T1
ON SCS# = T1S# AND T1C# = '001'
LEFT JOIN SC AS T2
ON SCS# = T2S# AND T2C# = '002'
LEFT JOIN SC AS T3
ON SCS# = T3S# AND T3C# = '003'
LEFT JOIN SC AS T4
ON SCS# = T4S# AND T4C# = '004'
WHERE studentS#=SCS# and
ISNULL(T1score,0) + ISNULL(T2score,0) + ISNULL(T3score,0) + ISNULL(T4score,0)
NOT IN
(SELECT
DISTINCT
TOP 15 WITH TIES
ISNULL(T1score,0) + ISNULL(T2score,0) + ISNULL(T3score,0) + ISNULL(T4score,0)
FROM sc
LEFT JOIN sc AS T1
ON scS# = T1S# AND T1C# = 'k1'
LEFT JOIN sc AS T2
ON scS# = T2S# AND T2C# = 'k2'
LEFT JOIN sc AS T3
ON scS# = T3S# AND T3C# = 'k3'
LEFT JOIN sc AS T4
ON scS# = T4S# AND T4C# = 'k4'
ORDER BY ISNULL(T1score,0) + ISNULL(T2score,0) + ISNULL(T3score,0) + ISNULL(T4score,0) DESC);
23、统计列印各科成绩,各分数段人数:课程ID,课程名称,[100-85],[85-70],[70-60],[ <60]
SELECT SCC# as 课程ID, Cname as 课程名称
,SUM(CASE WHEN score BETWEEN 85 AND 100 THEN 1 ELSE 0 END) AS [100 - 85]
,SUM(CASE WHEN score BETWEEN 70 AND 85 THEN 1 ELSE 0 END) AS [85 - 70]
,SUM(CASE WHEN score BETWEEN 60 AND 70 THEN 1 ELSE 0 END) AS [70 - 60]
,SUM(CASE WHEN score < 60 THEN 1 ELSE 0 END) AS [60 -]
FROM SC,Course
where SCC#=CourseC#
GROUP BY SCC#,Cname;
24、查询学生平均成绩及其名次
SELECT 1+(SELECT COUNT( distinct 平均成绩)
FROM (SELECT S#,AVG(score) AS 平均成绩
FROM SC
GROUP BY S#
) AS T1
WHERE 平均成绩 > T2平均成绩) as 名次,
S# as 学生学号,平均成绩
FROM (SELECT S#,AVG(score) 平均成绩
FROM SC
GROUP BY S#
) AS T2
ORDER BY 平均成绩 desc;
25、查询各科成绩前三名的记录:(不考虑成绩并列情况)
SELECT t1S# as 学生ID,t1C# as 课程ID,Score as 分数
FROM SC t1
WHERE score IN (SELECT TOP 3 score
FROM SC
WHERE t1C#= C#
ORDER BY score DESC
)
ORDER BY t1C#;
26、查询每门课程被选修的学生数
select c#,count(S#) from sc group by C#;
27、查询出只选修了一门课程的全部学生的学号和姓名
select SCS#,StudentSname,count(C#) AS 选课数
from SC ,Student
where SCS#=StudentS# group by SCS# ,StudentSname having count(C#)=1;
28、查询男生、女生人数
Select count(Ssex) as 男生人数 from Student group by Ssex having Ssex='男';
Select count(Ssex) as 女生人数 from Student group by Ssex having Ssex='女';
29、查询姓“张”的学生名单
SELECT Sname FROM Student WHERE Sname like '张%';
30、查询同名同性学生名单,并统计同名人数
select Sname,count() from Student group by Sname having count()>1;;
31、1981年出生的学生名单(注:Student表中Sage列的类型是datetime)
select Sname, CONVERT(char (11),DATEPART(year,Sage)) as age
from student
where CONVERT(char(11),DATEPART(year,Sage))='1981';
32、查询每门课程的平均成绩,结果按平均成绩升序排列,平均成绩相同时,按课程号降序排列
Select C#,Avg(score) from SC group by C# order by Avg(score),C# DESC ;
33、查询平均成绩大于85的所有学生的学号、姓名和平均成绩
select Sname,SCS# ,avg(score)
from Student,SC
where StudentS#=SCS# group by SCS#,Sname having avg(score)>85;
34、查询课程名称为“数据库”,且分数低于60的学生姓名和分数
Select Sname,isnull(score,0)
from Student,SC,Course
where SCS#=StudentS# and SCC#=CourseC# and CourseCname='数据库'and score <60;
35、查询所有学生的选课情况;
SELECT SCS#,SCC#,Sname,Cname
FROM SC,Student,Course
where SCS#=StudentS# and SCC#=CourseC# ;
36、查询任何一门课程成绩在70分以上的姓名、课程名称和分数;
SELECT distinct studentS#,studentSname,SCC#,SCscore
FROM student,Sc
WHERE SCscore>=70 AND SCS#=studentS#;
37、查询不及格的课程,并按课程号从大到小排列
select c# from sc where scor e <60 order by C# ;
38、查询课程编号为003且课程成绩在80分以上的学生的学号和姓名;
select SCS#,StudentSname from SC,Student where SCS#=StudentS# and Score>80 and C#='003';
39、求选了课程的学生人数
select count() from sc;
40、查询选修“叶平”老师所授课程的学生中,成绩最高的学生姓名及其成绩
select StudentSname,score
from Student,SC,Course C,Teacher
where StudentS#=SCS# and SCC#=CC# and CT#=TeacherT# and TeacherTname='叶平' and SCscore=(select max(score)from SC where C#=CC# );
41、查询各个课程及相应的选修人数
select count() from sc group by C#;
42、查询不同课程成绩相同的学生的学号、课程号、学生成绩
select distinct AS#,Bscore from SC A ,SC B where AScore=BScore and AC# <>BC# ;
43、查询每门功成绩最好的前两名
SELECT t1S# as 学生ID,t1C# as 课程ID,Score as 分数
FROM SC t1
WHERE score IN (SELECT TOP 2 score
FROM SC
WHERE t1C#= C#
ORDER BY score DESC
)
ORDER BY t1C#;
44、统计每门课程的学生选修人数(超过10人的课程才统计)。要求输出课程号和选修人数,查询结果按人数降序排列,查询结果按人数降序排列,若人数相同,按课程号升序排列
select C# as 课程号,count() as 人数
from sc
group by C#
order by count() desc,c#
45、检索至少选修两门课程的学生学号
select S#
from sc
group by s#
having count() > = 2
46、查询全部学生都选修的课程的课程号和课程名
select C#,Cname
from Course
where C# in (select c# from sc group by c#)
47、查询没学过“叶平”老师讲授的任一门课程的学生姓名
select Sname from Student where S# not in (select S# from Course,Teacher,SC where CourseT#=TeacherT# and SCC#=courseC# and Tname='叶平');
48、查询两门以上不及格课程的同学的学号及其平均成绩
select S#,avg(isnull(score,0)) from SC where S# in (select S# from SC where score <60 group by S# having count()>2)group by S#;
49、检索“004”课程分数小于60,按分数降序排列的同学学号
select S# from SC where C#='004'and score <60 order by score desc;
50、删除“002”同学的“001”课程的成绩
delete from Sc where S#='001'and C#='001';
;你好,请问你是jsp,php,asp呢。
一般在网页中显示数据库所查找到的信息,基本是一样的。
在网页中需要显示数据库信息的地方,写上语句,我以jsp为例子
一般网页开发都遵循MVC模式。至于什么是MVC模式,就不赘述了。
1一般对应数据库的那么表,我们会在webproject中创建一个javabean,也就是Namejava。
2里面的成员变量,就跟数据库的列名一样的,一般设置是private的,然后通过getter,setter方法来给予访问。
3另外数据库的链接 *** 作,最好有个java类创建数据库的连接及释放
4创建一个对name‘表的 *** 作的Java类。这里就称为。
主要是从数据库中查找所有的用户,返回当然是一个List集合
接下来,可以在网页中显示了
Listlist=();//具体方法不再赘述
for(inti=0;i
Namename=(Name)listget(i);
%>
//假设这里显示四个用户名
用户名:
%>
简单点的父子结构
select ccategory_id, cname, cparent_id from category c where cparent_id = 0
union
select c1category_id, concat(c1name,'>','c2name') name, c2parent_id from category c1, category c2
where c1parent_id>0
and c1category_id = c2parent_id
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