下面给大家分享下sql server建库、建表、建约束技巧，下文介绍有文字有代码。
--创建School数据库之前：首先判断数据库是否存在，若存在则删除后再创建，若不存在则创建--
--exists关键字:括号里边能查询到数据则返回‘true' 否则返回‘false'
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if exists(select * from sysdatabases where name = 'School')--exists返回‘true'则执行删除数据库操作--drop database School--exists返回‘false'则表明数据库不存在，直接创建 create database Schoolon primary(--主数据库文件--name = 'School', --主数据文件逻辑名fileName = 'D:\project\School.mdf', --主数据文件物理逻辑名size = 5MB, --初始值大小maxsize = 100MB, --最大大小filegrowth = 15% --数据文件增长量)log on(--日志文件--name = 'School_log',filename = 'D:\project\School_log.ldf',size = 2MB,filegrowth = 1MB)go |
----------------------------------------使用T-SQL创建employee数据库------------------------------------
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create database employeeon primary(--主要数据文件--name = 'employee1',filename = 'D:\project\employee1.mdf',size = 10MB,filegrowth = 10%),(--次要数据文件--name = 'employee2',filename = 'D:\project\employee2.ndf',size = 20MB,maxsize = 100MB,filegrowth = 1MB)log on(--第一个日志文件--name = 'employee_log1',filename = 'D:\project\employee_log1.ldf',size = 10MB,filegrowth = 1MB),(--第二个日志文件--name = 'employee_log2',filename = 'D:\project\employee_log2.ldf',size = 10MB,maxsize = 50MB,filegrowth = 1MB) |
---------------------------------查询已存在的数据库信息---------------------------
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select * from sysdatabases |
---------------------------------删除数据库------------------------------------
drop database School
---------------------------------创建Student数据库表----------------------------
--1、选择操作的数据库--
use School
go
--判断表是否存在--
if exists(select * from sysobjects where name = 'Student')
drop table Student
--2、创建表---
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create table Student(--具体的列名 数据类型 列的特征(是否为空)--StudentNo int identity(2,1) not null,LoginPwd nvarchar(20) not null,StudentName nvarchar(20) not null,Sex int not null,GradeId int not null,phone nvarchar(50) not null,BornDate datetime not null,Address nvarchar(255),Email nvarchar(50),IDENTITYcard varchar(18))go |
---查看所有数据库对象(数据库表)---
select * from sysobjects
drop table Student
----------------------创建subject课程表-------------------
-----1、判断表是否存在；若存在则删除再创建，若不存在则直接创建--------
if exists(select * from sysobjects where name = 'subject')
drop table subject
use School
go
---创建subject课程表--
create table subject
(
SubjectNo int not null identity(1,1),
SubjectName nvarchar(50),
ClassHour int,
GradeID int
)
----------------------------------------创建Result成绩表-------------------
-----1、判断表是否存在；若存在则删除再创建，若不存在则直接创建--------
if exists(select * from sysobjects where name = 'Result')
drop table Result
use School
go
---创建Result成绩表--
create table Result
(
StudentNo int not null,
SubjectNo int not null,
ExamDate Datetime not null,
StudentResult int not null
)
-----------------------------------------创建Grande年级表-------------------
-----1、判断表是否存在；若存在则删除再创建，若不存在则直接创建--------
if exists(select * from sysobjects where name = 'Grade')
drop table Grade
use School
go
---创建Grande年级表--
create table Grade
(
GradeId int not null,
GrandeName nvarchar(50)
)
-----------------------------------------T-SQL添加约束-------------------------
--给StudentNo添加主键约束---
alter table Student
add constraint pk_StuNo primary key(StudentNo)
--给身份证添加唯一约束--
alter table Student
add constraint uq_StuIdcard unique(IDENTITYcard)
---给地址address添加默认约束--
alter table Student
add constraint df_stuaddress default('地址不详') for Address
---删除地址address默认约束---
alter table Student
drop constraint df_stuaddress
----------出生日期添加检查约束--------
alter table Student
add constraint ck_stuBorndate check(Borndate > '1980-01-01')
---------与Grand（年级表）建立主外键关系--------
--1、添加Grade主键(操作Grade)---
alter table Grade
add constraint pk_graid primary key(GradeId)
--2、添加Grade外键(操作Student)--
alter table Student
add constraint fk_stuGradeID foreign key(GradeId) references Grade(GradeId)
-------------------给subject课程表添加约束-----------------------
----给subjectNo列添加主键约束------
alter table subject
add constraint pk_SubID primary key(SubjectNo)
------给课程名称subjectName添加非空约束；-----
-----with nocheck：已经存在数据不通过check约束-------
alter table subject with nocheck
add constraint ck_subName check(SubjectName is not null)
-----学时必须大于0-----
alter table subject with nocheck
add constraint ck_ClassHour check(ClassHour > 0)
-----与Grade年级表添加主外键约束----
alter table subject with nocheck
add constraint fk_GradeID foreign key(GradeID)
references Grade(GradeID)
----------给result成绩表添加约束------------
-------添加多个约束---------
alter table Result
add
constraint pk_No_subID_date primary key(StudentNo,SubjectNo,ExamDate),
constraint df_examdate default(getdate()) for ExamDate,
constraint ck_StudentResult check(StudentResult between 0 and 100),
constraint fk_StuNo foreign key(StudentNo) references Student(StudentNo),
constraint fk_subNo foreign key(SubjectNo) references Subject(SubjectNo)
--删除多个约束--
alter table Result
drop constraint pk_No_subID_date,fk_subNo,fk_StuNo,ck_StudentResult,df_examdate
--------更改列的数据类型----------
alter table Result
alter column StudentResult int
以上就是本文全部内容，希望大家喜欢。
