数据库|mysql教程
语句,添加,约束
数据库-mysql教程
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—–检查数据库是否存在——- use master go if exists(select*from sysdatabases where) drop database studentdb ——建数据库——– create database studentdb on primary( name=’student’, filename=’d:\data\student.mdf’, size=15, maxsize=25
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—–检查数据库是否存在——-
use master
go
if exists(select*from sysdatabases where)
drop database studentdb
——建数据库——–
create database studentdb
on primary(
name=’student’,
filename=’d:\data\student.mdf’,
size=15,
maxsize=25,
filegrowth=10%
)
log on (
name=’student_log’,
filename=’d:\data\student_log.ldf’,
size=20,
filegrowth=1
)
——修改数据库——–
alter database studentdb
modify file(
name=’student_log’,
maxsize=500
)
alter database studentdb
modify file(
name=’student’,
filegrowth=3
)
——创建表———
use studentdb
go
if exists(select * from sysobjects where)
drop table t_class
create table t_class(
C_Id char(6) primary key not null,
C_Number varchar(30) unique not null,
C_Depart varchar(30) null
)
use studentdb
go
if exists(select * from sysobjects where)
drop table t_student
create table t_student(
S_Id char(6) primary key not null,
C_Id char(6) not null,
S_Name varchar(30) null,
S_Gender char(2) check(S_Gender in(‘男’,’女’)) null,
S_Birthday datetime not null,
S_Nation char(10) null,
s_idcard varchar(18) check(len(s_idcard) in(15,18)) not null,
s_email varchar(50) check(s_email like ‘%@%’) not null
)
——-向表中添加信息———
insert into t_class values(’01’,’软件技术班’,’计算机技术系’)
insert into t_class values(’02’,’网络技术班’,’计算机技术系’)
insert into t_class values(’03’,’会计班’,’经贸系’)
insert into t_student (S_Id,C_Id,S_Name,S_Gender,S_Birthday,S_Nation) values (‘001′,’01’,’李林’,’男’,’1998-8-9′,’汉’)
insert into t_student (S_Id,C_Id,S_Name,S_Gender,S_Birthday,S_Nation) values (‘002′,’01’,’黄莺’,’女’,’1980-11-2′,’满’)
insert into t_student (S_Id,C_Id,S_Name,S_Gender,S_Birthday,S_Nation) values (‘003′,’03’,’张华’,’男’,’1991-3-19′,’汉’)
——修改信息－－－－－－－－－
update t_student set S_Name=’李大林’ where S_Id=001
——–显示男同学的信息－－－－－－
select * from t_student where S_Gender=’男’
———显示特定信息－－－－－
select * from t_student where year(S_Birthday)=1998
——–删除特定信息－－－－－－－
delete from t_student where C_Id=’01’
select * from t_student
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