SQL基础：SQL Server 数据库基础编程详解

use master
go

–判断是否存在该数据库，存在就删除
if (exists (select * from sys.databases where name = ‘testHome’))
drop database testHome
go
–创建数据库，设置数据库文件、日志文件保存目录
create database testHome
on(
name = ‘testHome’,
filename = ‘c:\data\students.mdf’
)
log on(
name = ‘testHome_log’,
filename = ‘c:\data\testHome_log.ldf’
)
go

if (exists (select * from sys.databases where name = ‘testHome’))
drop database testHome
go
create database testHome
–默认就属于primary主文件组，可省略
on primary (
–数据文件的具体描述
name = ‘testHome_data’, –主数据文件的逻辑名
fileName = ‘c:\testHome_data.mdf’, –主数据文件的物理名
size = 3MB, –主数据文件的初始大小
maxSize = 50MB, –主数据文件增长的最大值
fileGrowth = 10% –主数据文件的增长率
)
–日志文件的具体描述，各参数含义同上
log on (
name = ‘testHome_log’,
fileName = ‘c:\testHome_log.ldf’,
size = 1MB,
fileGrowth = 1MB
)
go

if (exists (select * from sys.databases where name = ‘testHome’))
drop database testHome
go
create database testHome
–默认就属于primary主文件组，可省略
on primary (
–数据文件的具体描述
name = ‘testHome_data’, –主数据文件的逻辑名
fileName = ‘c:\testHome_data.mdf’, –主数据文件的物理名
size = 3MB, –主数据文件的初始大小
maxSize = 50MB, –主数据文件增长的最大值
fileGrowth = 10% –主数据文件的增长率
),
–次数据文件的具体描述
(
–数据文件的具体描述
name = ‘testHome2_data’, –主数据文件的逻辑名
fileName = ‘c:\testHome2_data.mdf’, –主数据文件的物理名
size = 2MB, –主数据文件的初始大小
maxSize = 50MB, –主数据文件增长的最大值
fileGrowth = 10% –主数据文件的增长率
)
–日志文件的具体描述，各参数含义同上
log on (
name = ‘testHome_log’,
fileName = ‘c:\testHome_log.ldf’,
size = 1MB,
fileGrowth = 1MB
),
(
name = ‘testHome2_log’,
fileName = ‘c:\testHome2_log.ldf’,
size = 1MB,
fileGrowth = 1MB
)
go

–判断某个表或对象是否存在
if (exists (select * from sys.objects where name = ‘classes’))
print ‘存在’;
go
if (exists (select * from sys.objects where object_id = object_id(‘student’)))
print ‘存在’;
go
if (object_id(‘student’, ‘U’) is not null)
print ‘存在’;
go

–判断该列名是否存在，如果存在就删除
if (exists (select * from sys.columns where object_id = object_id(‘student’) and name = ‘idCard’))
alter table student drop column idCard
go
if (exists (select * from information_schema.columns where table_name = ‘student’ and column_name = ‘tel’))
alter table student drop column tel
go

–判断是否存在当前table
if (exists (select * from sys.objects where name = ‘classes’))
drop table classes
go
create table classes(
id int primary key identity(1, 2),
name varchar(22) not null,
createDate datetime default getDate()
)
go
if (exists (select * from sys.objects where object_id = object_id(‘student’)))
drop table student
go
–创建table
create table student(
id int identity(1, 1) not null,
name varchar(20),
age int,
sex bit,
cid int
)
go

–添加字段
alter table student add address varchar(50) not null;
–修改字段
alter table student alter column address varchar(20);
–删除字段
alter table student drop column number;

–添加多个字段
alter table student
add address varchar(22),
tel varchar(11),
idCard varchar(3);

–判断该列名是否存在，如果存在就删除
if (exists (select * from sys.columns where object_id = object_id(‘student’) and name = ‘idCard’))
alter table student drop column idCard
go
if (exists (select * from information_schema.columns where table_name = ‘student’ and column_name = ‘tel’))
alter table student drop column tel
go

–添加新列、约束
alter table student
add number varchar(20) null constraint no_uk unique;
–增加主键
alter table student
add constraint pk_id primary key(id);
–添加外键约束
alter table student
add constraint fk_cid foreign key (cid) references classes(id)
go
–添加唯一约束
alter table student
add constraint name_uk unique(name);
–添加check约束
alter table student with nocheck
add constraint check_age check (age > 1);
alter table student
add constraint ck_age check (age >= 15 and age <= 50)
–添加默认约束
alter table student
add constraint sex_def default 1 for sex;
–添加一个包含默认值可以为空的列
alter table student
add createDate smalldatetime null
constraint createDate_def default getDate() with values;

—– 多个列、约束一起创建——–
alter table student add
/*添加id主键、自增*/
id int identity constraint id primary key,
/* 添加外键约束*/
number int null
constraint uNumber references classes(number),
/*默认约束*/
createDate decimal(3, 3)
constraint createDate default 2010-6-1
go

–删除约束
alter table student drop constraint no_uk;

insert into classes(name) values(‘1班’);
insert into classes values(‘2班’, ‘2011-06-15’);
insert into classes(name) values(‘3班’);
insert into classes values(‘4班’, default);

insert into student values(‘zhangsan’, 22, 1, 1);
insert into student values(‘lisi’, 25, 0, 1);
insert into student values(‘wangwu’, 24, 1, 3);
insert into student values(‘zhaoliu’, 23, 0, 3);
insert into student values(‘mazi’, 21, 1, 5);
insert into student values(‘wangmazi’, 28, 0, 5);
insert into student values(‘jason’, null, 0, 5);
insert into student values(null, null, 0, 5);

insert into student
select ‘bulise’ name, age, sex, cid
from student
where name = ‘tony’;

–多条记录同时插入
insert into student
select ‘jack’, 23, 1, 5 union
select ‘tom’, 24, 0, 3 union
select ‘wendy’, 25, 1, 3 union
select ‘tony’, 26, 0, 5;

–查询数据
select * from classes;
select * from student;
select id, ‘bulise’ name, age, sex, cid from student
where name = ‘tony’;
select *, (select max(age) from student) from student
where name = ‘tony’;

–修改数据
update student set name = ‘hoho’, sex = 1 where id = 1;

–删除数据（from可省略）
delete from student where id = 1;

–备份、复制student表到stu
select * into stu from student;
select * into stu1 from (select * from stu) t;
select * from stu;
select * from stu1;–备份、复制student表到stu
select * into stu from student;
select * into stu1 from (select * from stu) t;
select * from stu;
select * from stu1;

–查询student相关信息
exec sp_help student;
exec sp_help classes;