1.默认约束
2.主键约束，（唯一约束+非空约束），
设置了主键的字段在赋值的时候不能重复，stuID为主键则1，下一个就不能为1
3.唯一约束（允许一行为空），
4.check约束
5.主外建约束 （主表 子表）一对多
添加完整性约束
外键约束：
学生基本信息表（主表）的学生编号是主键
考试成绩表的学生（子表）的编号是外键
一个表在不同的关系中既可以是主表又可以是子表
主外建是一对多
”数据字典“
哪一个是外键表，就给他添加外建约束
3个一致：1 外键表外键与主键数据类型一致（语法一只）
2 长度：外键>=主键表；长了也没有意义
3 名称一致。
如果sql语句写的错误很多，只需要看第一行和最后一行错误。
如果不多，就仔细看下。
通配符----
select * from employee
-- 插入一条忘记加入的字段 直接在表的后面添上add
--alter table employee add emName varchar(20) not null
alter table employee
add constraint PK_emId primary key (emId)
alter table employee
add constraint CK_age CHECK(age between 20 and 55)
alter table employee
add constraint DF_address default(‘地址不详‘) for address
alter table employee
add constraint UQ_emName unique (emName)
--外键表
alter table employee
add constraint FK_emtypeId
foreign key(emtypeId) references mangertype(mantypeId)
标示列可以不是主键，种子和自增量必须是int，标示列不能编辑
先自增，再验证，最后插入
在数据关系图里 带钥匙的一方是主键表
-----------------------
插入（insert）
1.匹配，
2.多行数据
备份表 select * into student1 from student
就生成一个新的student1
select * into student1 from student
select * from student1
--将字段名备份，但是所建的约束消失
select stuNoid,stuName,sex,age,address into student2 from student
select * from student2
--将字段名更改，加as即可
select stuNoid as haha,stuName as gaga,sex as hello,age,address into student3 from student
select * from student3
select * from student1
use wangwang
go
create table employee
(
empId int identity primary key,
empName varchar(20) not null,
sex bit not null,
age int ,
address varchar(20)
)
go
select * from employee
---接下来将student1表中的数值插入到employee中
/*insert into employee
(empId,empName,sex,age,address)
select
(stuNoId,stuName,sex,age,address)
from stdent1
where age>20
*/
----插入多行数据union方法
insert student1
(stuNoId,stuName,sex,age,address)
select--不支持default关键字要用‘’括起来，当两行数据一致时，默认为一行
‘1‘,‘liuzhao‘,‘1‘,‘31‘,‘default‘ union
select
‘1‘,‘liu‘,‘1‘,‘28‘,‘default‘ union
select
‘1‘,‘zhao‘,‘1‘,‘31‘,‘default‘
select * from student1
select * from student1 order by age desc（asc）
------------------------------
模糊查询
alter table student add groupId int
select * from student
insert student
(stuNoId,stuName,sex,age,address)
select
‘5‘,‘zhaoliu‘,‘1‘,‘30‘,‘南昌路‘ union
select
‘6‘,‘zhao‘,‘1‘,‘31‘,‘南路‘ union
select
‘7‘,‘liu‘,‘1‘,‘32‘,‘昌路‘
---模糊查询
select * from student where address like ‘%南%‘
select * from student where stuName like ‘wangwu[2-4]‘
select * from student where stuName like ‘wangwu[^2-4]%‘--取反
--加上% 可以将wangwua查出来
select * from student where stuName like ‘wangwu[^2-4]%‘
----
use wangwang
go
create table person
(
perId int identity primary key,
personId int not null--身份证
)
go
--给身份证添加约束，假如身份证五位数字
/*select * from person
alter table person
add constraint CK_personId CHECK(personId like [0-4],[0-4],[0-4],[0-4],[0-4])
go*/
--更改
update student set age=age+1
select * from student where groupId=1
update student set age=age+2,stuName=stuName+‘mm‘
where groupId=1
--删除
delete from student where groupId=1
select * from student
delete from student-- 删除表
truncate table student--删除表（效率快 ）
------------------------------------
SQL 结构化查询语言
T-Sql是SQL的加强版
-----------------------------
查询：
1.基础查询2.聚合函数3.链接查询4.子查询
--更改
update student set age=age+1
select * from student where groupId=1
update student set age=age+2,stuName=stuName+‘mm‘
where groupId=1
--删除
delete from student where groupId=1
select * from student
delete from student-- 删除表
truncate table student--删除表（效率快 ）
-------------------------------查询
use wangwang
go
select * from student where address=‘南昌路‘
/*select
colname1 as 别名,
colname2 as 别名,
from
tableName
where
条件
group by
分组
having
分组后的筛选
order by
排序
*/
--起别名
select *,‘姓名‘=stuName from student
select *,stuName as ‘as用法‘ from student
--给表起名
select *,stuName as ‘as用法‘ from student as Stu
alter table student add haha varchar(20)
select * from student
update student set haha=‘mm‘ where age>31
select * from student where haha is null
--string a=null与a=‘‘是不一样的 null与空
select * from student where haha is null
select * from student where haha=‘‘
select * from student order by stuNoId asc
-------------------分页处理，关键字--top--percent
select top 5 * from student--每页出现5行
select top 50 percent * from student--每页出现总体的百分之n，进1法
--排序
select * from student order by age desc--降序号
select * from student order by stuNoId asc--升序
-----函数。
select ‘aaa‘ as ‘列明‘
--查询an在后面的英语中出现的序列
select CHARINDEX(‘an‘,‘my name is wangwang‘)
--查询an在后面的英语中出现的序列,前面14个不算，从第15开始查找
select CHARINDEX(‘an‘,‘my name is wangwang‘,14)
-----查询长度
select LEN(‘123456‘)
select address,LEN(address) as ‘ cahngdu‘ from student
-----------ltrim()可取空格
select * from student where ltrim(address)=‘ 天津路‘--左空格
select * from student where ltrim(ltrim(address))=‘ 天津路‘--俩边空各
---截取字符串right
select RIGHT(‘sgdsggueui‘,4) as ‘截取后显示‘
select left(‘sgdsggueui‘,4) as ‘截取后显示‘
----------替换
select replace(‘sfsfhufhsh‘,‘sh‘,‘AA‘)--将sh换成AA
select replace(‘sfsfhufhsh‘,‘s‘,‘9‘)--将sh换成AA
------------日期函数
select GETDATE()--得到当前日期
select DATEADD(DD,10000,‘93-07-22‘)--活一万天
select DATENAME(DW,GETDATE())--今天星期几
select DATENAME(WW,GETDATE())--今天是今年的第几周
select * from student
select convert(varchar(2),age)+address as ‘新的列明‘ from student
select age + convert( int,address) as ‘新的列明‘ from student--有错误
---------------------------------------------------
案例1
create table card
(
cId int identity primary key,
CaId varchar(20) not null
)
go
insert card values (‘fifuejf789io0i658‘)
select * from card
update card set CaId = replace(CaId,‘i‘,‘1‘)
--update replace(CaId,‘i‘,‘1‘) from card
select REPLACE(replace(CaId,‘i‘,‘1‘),‘o‘,‘0‘) from card
select * into card2 from card
select * from card2
update card2 set card=REPLACE(REPLACE(CaId,‘i‘,‘1‘),‘o‘,‘0‘)
----------------------------------------------------------------------
SQL编程
变量分为:1.局部变量，以@符号前缀，先声明再赋值
赋值：set @变量名=值 select @变量名=值
set @name=zhangsan
select studentNo from student where [email protected]
李文才：
declare @name varchar(8)
set @name=‘李文才‘
select @No=studentNo from student where [email protected]
declare @No int//定义
print‘学号‘[email protected]
查询出学号+-1的相邻的同学。
select * from student where [email protected]+1 or [email protected]
----------------------------------------------------
insert into Class(GradeId,ClassID) values (4,‘201‘)
@@IDENTITY
-------------------------------
DECLARE @TAG VARCHAR(1)
SET @TAG=‘*‘
PRINT @[email protected]
PRINT @[email protected][email protected]
PRINT @[email protected][email protected][email protected]
------DECLARE @xuehao int
set @xuehao =20011
select * from student where [email protected]//学生记录查出来
declare @year int
set @year=DateDiff(DY,‘1996-8-7‘,getdate())/365;年份
select * from student where [email protected]+1 or [email protected];
---------------------------------------
create database MySchool
on primary
(
name = ‘MySchool_data‘,
filename = ‘D:\project\MySchool_data‘,
size = 10mb,
maxsize = 100mb,
filegrowth=15%
)
log on
(
name = ‘MySchool_log‘,
filename = ‘D:\project\MySchool_log‘,
size = 3mb,
maxsize = 20mb,
filegrowth=1mb
)
if exists(select * from sysobjects where name = ‘Student‘)
drop table student
create table dbo.Student(
StudentNo int NOT NULL,
LoginPwd nvarchar(50) NOT NULL,
StudentName nvarchar(50) NOT NULL,
sex bit NOT NULL,
GradeId int NOT NULL,
Phone nvarchar(50) NULL,
Address nvarchar(255) NULL,
BornDate datetime NOT NULL,
Email nvarchar(50) NULL,
IdentityCard varchar(18) NOT NULL
)
if exists(select * from sysobjects where name = ‘Subject‘)
drop table subject
create table dbo.Subject(
SubjectNO int IDENTITY(1,1) NOT NULL,
SubjectName nchar(50) NOT NULL,
ClassHour int NOT NULL,
GradeId int NOT NULL
)
if exists(select * from sysobjects WHERE name = ‘Result‘)
drop table Result
create table dbo.Result(
StudentNo int NOT NULL,
SubjectNo int NOT NULL,
StudentResult int NOT NULL,
ExamDate datetime NOT NULL
)
if exists(select * from sysobjects where name = ‘Grade‘)
drop table Grade
create table Grade(
GradeId int IDENTITY(1,1) NOT NULL,
GradeName nvarchar(50) NOT NULL
)
--向Grade表插入数据
INSERT INTO Grade VALUES(‘S1‘)
--向Subject表插入数据
INSERT INTO Subject VALUES(‘Winforms‘,20,1)
--向Student表插入数据
INSERT INTO Student VALUES(‘10000‘,‘GuoJing‘,‘郭靖‘,1,1,02088762106,‘天津市河西区‘,‘1987-09-08 00:00:00‘,‘[email protected]‘,111111)
--向Result表插入数据
INSERT INTO Result VALUES(‘10001‘,2,70.6,‘2013-02-15 00:00:00‘)
----------------------------------------------------------------------
USE master --设置当前数据库为master，以便访问sysdatabases表
GO
IF EXISTS(SELECT * FROM sysdatabases WHERE name =‘MySchool‘)
DROP DATABASE MySchool
GO
CREATE DATABASE MySchool
ON (
name=‘MySchool_data‘,
FILENAME=‘F:\project\MySchool_data.mdf‘,
SIZE=10mb, --主数据文件的初始大小
MAXSIZE=100mb, --主数据文件增长的最大值
FILEGROWTH=15% --主数据文件的增长率
)
LOG ON
(
/*--日志文件的具体描述，各参数含义同上--*/
NAME=‘MySchool_log‘,
FILENAME=‘F:\project\MySchool_log.ldf‘,
SIZE=3mb,
MAXSIZE=20mb, --日志文件增长的最大值
FILEGROWTH=1mb
)
GO
/*--查询得到Student表的信息--*/
USE MySchool
GO
SELECT * FROM sysobjects
/*--案例：使用SQL语句删除表Student学生--*/
IF EXISTS(SELECT * FROM sysobjects WHERE name=‘Student‘)
DROP TABLE Student
/*--学时2--*/
/*--案例：使用SQL语句创建Student表--*/
CREATE TABLE [dbo].[Student](
[StudentNo] [int] NOT NULL,
[LoginPwd] [nvarchar](50) NOT NULL,
[StudentName] [nvarchar](50) NOT NULL,
[Sex] bit NOT NULL,
[GradeId] [int] NOT NULL,
[Phone] [nvarchar](50) NULL,
[Address] [nvarchar](255) NULL,
[BornDate] [datetime] NOT NULL,
[Email] [nvarchar](50) NULL,
[IdentityCard] [varchar](18) NOT NULL
)
GO
/*--案例：使用SQL语句创建Subject科目表--*/
IF EXISTS(SELECT * FROM sysobjects WHERE name=‘Subject‘)
DROP TABLE Subject
CREATE TABLE [dbo].[Subject](
[SubjectNo] [int] IDENTITY(1,1) NOT NULL,
[SubjectName] [nchar](50) NOT NULL,
[ClassHour] [int] NOT NULL,
[GradeId] [int] NOT NULL
)
GO
/*--案例：使用SQL语句创建Result结果表--*/
IF EXISTS(SELECT * FROM sysobjects WHERE name=‘Result‘)
DROP TABLE ResultResult
CREATE TABLE [dbo].[Result](
[StudentNo] [int] NOT NULL,
[SubjectNo] [int] NOT NULL,
[StudentResult] [int] NOT NULL,
[ExamDate] [datetime] NOT NULL
)
GO
/*--案例：使用SQL脚本创建Student学生表--*/
IF EXISTS(SELECT * FROM sysobjects WHERE name=‘Student‘)
DROP TABLE Student
CREATE TABLE [dbo].[Student](
[StudentNo] [int] NOT NULL,
[LoginPwd] [nvarchar](50) NOT NULL,
[StudentName] [nvarchar](50) NOT NULL,
[Sex] [bit] NOT NULL,
[GradeId] [int] NOT NULL,
[Phone] [varchar](50) NULL,
[Address] [nvarchar](255) NULL,
[BornDate] [datetime] NOT NULL,
[Email] [varchar](50) NULL,
[IdentityCard] [varchar](18) NOT NULL,
)
GO
/*--案例：使用SQL脚本创建Grade年级表--*/
IF EXISTS(SELECT * FROM sysobjects WHERE name=‘Grade‘)
DROP TABLE Grade
CREATE TABLE [dbo].[Grade](
[GradeId] [int] IDENTITY(1,1) NOT NULL,
[GradeName] [nvarchar](50) NOT NULL
)
GO
alter table Student
add Constraint pk_StudentNo primary key(StudentNo)
--Student表中的唯一约束
alter table Student
add Constraint uq_IdentityCard unique(IdentityCard)
--student表中的默认约束
alter table Student
add Constraint df_Address default(‘地址不详‘) for Address
--student表中的检查约束
alter table Student
add Constraint ck_BornDate check(BornDate>‘1980-01-01‘)
--外键约束
alter table Grade
add Constraint pk_GradeId PRIMARY key(GradeId)
alter table Student
add Constraint fk_Grade foreign key(GradeId)
references Grade(GradeId)
go
--向Subjiect添加约束
alter table Subject
add Constraint pk_SubjectNo primary key(SubjectNo)
alter table Subject
add Constraint ck_ClassHour check(ClassHour>0)
ALTER TABLE Subject --非空约束（课程名称）
ADD CONSTRAINT CK_SubjectName CHECK (SubjectName is not null)
alter table subject
add Constraint fk_GradeId foreign key(GradeId)
references Grade(GradeId)
go
--使用SQL语句创建Result表的约束
ALTER TABLE Result --主键约束（学号、科目号、日期）
ADD CONSTRAINT PK_Result PRIMARY KEY
(StudentNo, SubjectNo, ExamDate)
ALTER TABLE Result --默认约束（日期为系统当前日期）
ADD CONSTRAINT CK_ExamDate DEFAULT (getdate()) FOR ExamDate
ALTER TABLE Result --检查约束（分数不能大于100，小于0）
ADD CONSTRAINT CK_StudentResult CHECK
(StudentResult BETWEEN 0 AND 100)
ALTER TABLE Result --外键约束（主表Student和从表Result建立关系）
ADD CONSTRAINT FK_StudentNo
FOREIGN KEY (StudentNo) REFERENCES Student (StudentNo)
ALTER TABLE Result --外键约束（主表Subject和从表Result建立关系）
ADD CONSTRAINT FK_SubjectNo
FOREIGN KEY (SubjectNo) REFERENCES Subject (SubjectNo)
GO
--------------------------------------------------------------------
DATEDIFF(DY, BornDate, GETDATE())/365
DatePart()函数用于返回日期或者时间的单独部分，比如年、月、日、小时、分
例如 DatePart(YY,BornDate)
返回出生年月中的年份
可以通过DatePart()函数得到学号20011的学生大一岁和小一岁的学生
declare @year datetime
select @year= BornDate from Student where StudentNo=20011
select StudentName,sex,datepart(YY,BornDate) as BornDate from Student where StudentNo=20011 or datepart(YY,BornDate)= @year+1 or datepart(YY,BornDate)[email protected]
--select * from Student where ABS(DATEDIFF(DAY,@year,BornDate))/365<=1
--select * from Student where DATEDIFF(DAY,@year,BornDate)/365<=1 and DATEDIFF(DAY,BornDate,@year)/365<=1
--select * from Student
----------------------------------------------------------------------------------------
--子查询 总是用小括号括起来，先执行螺号里面的子查询，然后才执行外围的父查询
--注意：将子查询和比较运算符联合使用，必须保证子查询的返回结果为一个。
--查看比李思文小的学生
--declarre @date datetime
--select BornDate as ‘李斯文的出生日期‘ from Student where StudentName=‘李斯文‘
--select * from Student
--where BornDate > (select BornDate as ‘李斯文的出生日期‘ from Student where StudentName=‘李斯文‘)
-------------------------------------------------------
高级查询
简单子查询的用法
declare @Birthday datetime
select @Birthday = BornDate from student where studentName=‘李斯文‘;
select studentName,sex from student where BornDate>@Birthday
------------------------------
select StudentResult from Result
where SubjectNo=(select SubjectNo from Subject where SubjectName=‘C# OOP‘) and
ExamDate=(select max(ExamDate) from Result where SubjectNo=(select SubjectNo from Subject where SubjectName=‘C# OOP‘))
--select max(ExamDate) from Result where SubjectNo=(select SubjectNo from Subject where SubjectName=‘C# OOP‘)
--1.从课程名称查询出课程编号，2.从课程编号查询出最近（大）日期，从1和2一起查询出考试成绩。
--查询Java课程考试成绩为60分的学生名单--in 关键字：查询出来的结果可能是多个
select StudentName from Student where StudentNo in
(
select StudentNo from Result where SubjectNo=(select SubjectNo from Subject where SubjectName=‘Java Logic‘)
and
StudentResult=60
)
------------------------------------------
--in 用法 查询结果有多个
select StudentNo,studentName from Student where GradeId in (select GradeId from Grade where GradeName = ‘S1‘)
------------------------------------------------------------------------------
聚合函数：sum avg min max count（null列不计算在rpu内）
分组：select groupId,avg(age) from student
group by groupId
having avg(age)<=30 刷选
where 和 having的区别：where 对表中的原始数据进行帅选，
having对分组后使用聚合函数计算后的数据进行帅选
having一般与group by结合使用
------------------------------------------
视图
视图名称
creatview view_name(view_colum_name)
As query_expression（查询表达式）
[with check option]（添加约束条件）
-------------------------------------------------
--分组查询 Group by 在select 语句查询的最后。
select studentResult ,sum(subjectNo) from Result group by studentResult
--出现Group by 一般就会出现聚合函数
--查询学生每一门课程的平均成绩
--要求显示学生姓名，课程名称，
--科目ji的平均分--如何将studentNo与studentName联系在一起？
select SubjectNo , AVG(studentResult)From Result group by subjectNo --left on student.
select SubjectName ,AVG(studentResult)from Result
left join subject on
subject.SubjectNO=result.subjectNo ///////left join 外表 on 俩表相等的字段
group by SubjectName --学生的平均分
--select studentNo ,AVG(studentResult) from Result where StudentNo=1000 group by studentNo
--查询课程的成绩 显示课程名称以及所对应的成绩
--left join 左链接！！！！ 主从表的关系右边的是主表 on
select SubjectNo , AVG(studentResult)From Result group by subjectNo
select Result.StudentResult,SubjectName from Result
Left join Subject on --left join +主表 on后面加俩个表相同的字段
subject.SubjectNO=result.subjectNo
----------------------------------------------------------
事务 视图 索引
begin transaction
declare @error int
set @error=0
update bank set currentmoney=currentmoney-1000 where customername=‘张三‘
set @[email protected][email protected]@error 错误信息 全局变量
update bank set currentmoney=currentmoney+1000 where customername=‘李四‘
set @[email protected][email protected]@error
给客户一个可视化的结果，
if(@error<>0)
begin
print ‘转账失败，重重新操作‘
rollback transaction 回滚
end
esle
begin
print ‘转账成功张三给李四转了1000‘
commit transaction 提交给数据库
end
go
1.业务逻辑需要多个T_SQL语句来执行
create table bank
(
customername varchar(5)
currentmoney int
)
事务属性：原子性（各个步骤不可以再分，要么都执行，要么都不执行）
一致性 当事务完成时，数据必须处于一致状态
隔数离性 并发实物之间彼此隔离，独立，不应依赖其他
永久性
开始事务： begin transaction
提交事务：commit transaction
回滚事务：roollback transaction
事务是解决可能存在的问题
------------------------------------------------------
begin transaction
declare @error int
set @error=0
insert into Result values(113,2,150,GETDATE())
set @[email protected][email protected]@error
if(@error<>0)
begin
print ‘插入失败‘
rollback transaction
end
else
begin
print ‘插入成功‘
commit transaction
end
select * from Result
---------------------------------------------------------------------------
索引：根据索引键查找定数据行
汉语字典中的汉字按“页”存放，一般都有汉语拼音的目录（索引），偏旁部首目录等
sql中的数据也是按页存放
索引;shi sql编排数据的方法
唯一索引，主键索引，聚集索引，
--------------------------------------------------
存储过程
系统存储过用程的名字一般以sp_开头
扩展存储一般xp
调用存储
execute 过程名 [参数] 或者 exec 过程名 [参数]
create proc[edure] 存储过程名
@参数1 数据类型=默认值 output
。。。。。。。
@参数n 数据类型=默认值 output
as
sql语句
go