数据库最全的sql语句总结大全

时间：2024.5.4

CREATE DATABASE edu ON(

NAME=edu_data,

FILENAME='c:/edu_data.mdf',

SIZE=10M,

MAXSIZE=1024M,

FILEGROWTH=1M)

LOG ON(

NAME=edu_log,

FILENAME='c:/edu_log.ldf',

SIZE=5M,

MAXSIZE=100M,

FILEGROWTH=10%)

create database st

use st

drop database st

create schema st

drop schema cascade

1 create table st.Student(....);

2 create schema st

create table Student(...);

3 set search_path to st;

create table Student(..);

create table Student

(Sno char(9) primary key,

Sname char(20) unique,

Ssex char(20) check(sex=''or sex='')

)

create table sc

(Sno char(9)

Cno char(4)

Grade smallint

primary key (Sno,Cno)

foreign key(Sno) references Student(Sno),

foreign key(Cno) references Course(Cno));

alter table Student add Scom datetime;

add unique(Cname);

alter column Sage smallint;

create unique(每一个索引值对应唯一数据) index student on Student(Sno);

create cluster index Stusname on Student(Sname);

drop index st.student;

select 20xx-Sage age,distinct Sno

from Student

where Sdept in('is','cs');

select *

from Student

where Sno like'212';

where rtrim(Sname) like '_liu%\' escape'\';

select Sno

from SC

where Grade ie null

order by Grade desc(降序);

select count(distict *) sum avg max min

from Student;

分组 grop by 分组后聚集函数作用于每一个组

select Cno,count(Sno)集合查询使用了聚集函数或在group by 后 from SC

group by Cno;

select sdept,count(*)

from Student

where ssex=''

group by sdept

order by sdept desc;

having 对集合特性的限制

select Sno,count(Cno)

from SC

where Grade>=85

group by Sno

having count(*)>3

order by count(*)desc;

select Student.Sno,Sname,Cno,grade

from Student,SC

whereStudent.Sno=SC.Sno;(两表连接条件)

select Studednt.Sno,Sname,Cnno,grade

from Student inner join SC on Student.Sno=SC.Sno

where sdept='CS';

select S1.Sno,S1.Sname,S1.Sdept

from Student S1,Student S2

where S1.Sdept=S2.Sdept and S2.Sname='';

(选修了课程的学生信息)

select s1.Sno,Sname,Cno,grade

from Student S1 left outer join SC s2 on s1.Sno=s2.Sno order by s1,Sno;

课程被选修的情况

right outer join

所有情况

full outer join

select s=Student.sno,Sname,avg(grade) 平均成绩

from Student inner join SC on Student.Sno=SC.Sno

group by Student.Sno,Sname

having avg(grade)>=85

order by 平均成绩 desc;

any/all

select Sname,Sage

from Student

where Sdept<>'cs' and Sage<any(select Sage

from Student

where Sdept='cs')

where Sage<(select max(Sage)

from Student

where Sdept='cs')and Sdept<>'cs';(all与<min)

select Sname

from Student

where exists

(select *

from SC

where Sno=Student.Sno and Cno='1'

)

select Sname

from Student,SC

where Student.Sno=SC.Sno and SC.cno='1';

select Sno,Cno

from SC x

where grade>=(select avg(grade)

from SC y

where y.Sno=x.Sno);

select Sno,Cno

from SC x,SC y

where y.Sno=x.Sno

group by Sno,Cno

having grade>avg(grade);

select Sname

from Student

where not exists

(select *

from Course

where not exists

(select *

from SC

where Sno=Student.Sno and Cno=Course.Cno));

select Sno

from Student

where not exists

(select *

from Course

where Cno in(select Cno from SC where Sno='1')

and not exist(select *

from SC

where Sno=Student.Sno and Cno=Course.Cno));

并交差

seletc Sno

from SC

where Cno='1'

union

select Sno

from SC

where Cno='2';

select distinct Sno

from SC'

where Cno='1'or Cno='2';

intersect 对应 and

seletc Sno

from SC

where Cno='1'

intersect

select Sno

from SC

where Cno='2';

select Sno

from SC

where Cno='1' and Sno in

(select Sno

from SC

where Cno='2');

seletc Sno

from SC

where Cno='1'

except

select Sno

from SC

where grade<19;

insert into Student

values ('1','','',19,'cs');

insert into Student(Sdept,Avgge) select Sdept,avg(Sage) from Student

group by Sdept;

update Student

set Sage=21,Sdept='is' where Sno='12';

update Student

set Sage=Sage+1;

update SC

set Grade=0

where Sno in

(seelct Sno

from Student

where Sdept='cs');

delete

from Student

where Sno='11';

delete from SC;

delete

from SC

where 'cs'=

(select Sdept

from Student

where Student.Sno=SC.Sno);

create view IS

select Sno,Sname,Sage from Student

where Sdept='is';

第二篇：[数据库]简单SQL语句总结

[数据库] 简单SQL语句总结

全篇以学生成绩的管理为例描述。

1.在查询结果中显示列名：

a.用as关键字：select name as '姓名' from students order by age

b.直接表示：select name '姓名' from students order by age

2.精确查找:

a.用in限定范围：select * from students where native in ('湖南', '四川')

b.between...and：select * from students where age between 20 and 30

c.“=”：select * from students where name = '李山'

d.like:select * from students where name like '李%' (注意查询条件中有“%”，则说明是部分匹配，而且还有先后信息在里面，即查找以“李”开头的匹配项。所以若查询有“李”的所有对象，应该命令：'%李%';若是第二个字为李，则应为'_李%'或'_李'或'_李_'。)

e.[]匹配检查符：select * from courses where cno like '[AC]%' (表示或的关系，与"in(...)"类似，而且"[]"可以表示范围，如：select * from courses where cno like '[A-C]%')

3.对于时间类型变量的处理

a.smalldatetime：直接按照字符串处理的方式进行处理，例如：

select * from students where birth > = '1980-1-1' and birth <= '1980-12-31'

4.集合函数

a.count()求和，如：select count(*) from students (求学生总人数)

b.avg(列)求平均，如：select avg(mark) from grades where cno=?B2?

c.max(列)和min(列)，求最大与最小

5.分组group

常用于统计时，如分组查总数：

select gender,count(sno)

from students

group by gender

(查看男女学生各有多少)

注意：从哪种角度分组就从哪列"group by"

对于多重分组，只需将分组规则罗列。比如查询各届各专业的男女同学人数，那么分组规则有：届别(grade)、专业(mno)和性别(gender)，所以有"group by grade, mno, gender"

select grade, mno, gender, count(*)

from students

group by grade, mno, gender

通常group还和having联用，比如查询1门课以上不及格的学生，则按学号(sno)分类有：select sno,count(*) from grades

where mark<60

group by sno

having count(*)>1

6.UNION联合

合并查询结果，如：

SELECT * FROM students

WHERE name like ?张%?

UNION [ALL]

SELECT * FROM students

WHERE name like ?李%?

7.多表查询

a.内连接

select g.sno,s.name,c.coursename

from grades g JOIN students s ON g.sno=s.sno

JOIN courses c ON g.cno=c.cno

(注意可以引用别名)

b.外连接

b1.左连接

select courses.cno,max(coursename),count(sno)

from courses LEFT JOIN grades ON courses.cno=grades.cno

group by courses.cno

左连接特点：显示全部左边表中的所有项目，即使其中有些项中的数据未填写完全。左外连接返回那些存在于左表而右表中却没有的行，再加上内连接的行。

b2.右连接

与左连接类似

b3.全连接

select sno,name,major

from students FULL JOIN majors ON students.mno=majors.mno

两边表中的内容全部显示

c.自身连接

select c1.cno,c1.coursename,c1.pno,c2.coursename

from courses c1,courses c2 where c1.pno=c2.cno

采用别名解决问题。

d.交叉连接

select lastname+firstname from lastname CROSS JOIN firstanme

相当于做笛卡儿积

8.嵌套查询

a.用关键字IN,如查询李山的同乡：

select * from students

where native in (select native from students where name=? 李山?)

b.使用关键字EXIST,比如，下面两句是等价的：

select * from students

where sno in (select sno from grades where cno=?B2?)

select * from students where exists

(select * from grades where

grades.sno=students.sno AND cno=?B2?)

9.关于排序order

a.对于排序order，有两种方法：asc升序和desc降序

b.对于排序order,可以按照查询条件中的某项排列，而且这项可用数字表示，如：

select sno,count(*) ,avg(mark) from grades

group by sno

having avg(mark)>85

order by 3

10.其他

a.对于有空格的识别名称，应该用"[]"括住。

b.对于某列中没有数据的特定查询可以用null判断，如select sno,courseno from grades where mark IS NULL

c.注意区分在嵌套查询中使用的any与all的区别，any相当于逻辑运算“||”而all则相当于逻辑运算“&&”

d.注意在做否定意义的查询是小心进入陷阱：

如，没有选修?B2?课程的学生：

select students.*

from students, grades

where students.sno=grades.sno

AND grades.cno <> ?B2?

上面的查询方式是错误的，正确方式见下方：

select * from students

where not exists (select * from grades

where grades.sno=students.sno AND cno='B2')

11.关于有难度多重嵌套查询的解决思想：

如，选修了全部课程的学生：

select *

from students

where not exists ( select *

from courses

where NOT EXISTS

(select *

from grades

where sno=students.sno

AND cno=courses.cno))

最外一重：从学生表中选，排除那些有课没选的。用not exist。由于讨论对象是课程，所以第二重查询从course表中找，排除那些选了课的即可。

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数据库 最全的sql语句总结大全

第二篇：[数据库]简单SQL语句总结

数据库最全的sql语句总结大全