–创建表
create table Employees
(
EmployeeID Int primary key ,
Name VarChar(10) NOT NULL,
Sex Char(2) default ’男’,
Birthdate Datetime NULL,
Address Varchar(50) NULL,
Phone Char(13) check (phone like ’000-[0_9]’),
Remark text
)
create table wage
(
EmployeeID Int foreign key references Employees(EmployeeID),
Name VarChar(10) NOT NULL,
Wage money NOT NULL,
Putdate Datetime NOT NULL,
)
–添加主键约束
alter table Employees
add constraint Employees_PK primary key (EmployeeID)
–添加外键约束
alter table wage
add constraint wage_FK foreign key (EmployeeID) references Employees(EmployeeID)
–删除约束
alter table wage
drop constraint wage_FK
–添加default约束
alter table Employees
add constraint a default (’unknown’) for name,
constraint b default (’男’) for sex,
constraint phone_check check(phone like ‘(\d{3})\d{9}’)
–删除列
alter table Employees
drop column Remark
–添加列
alter table Employees
add Remark text,
phone varchar(10)
–删除表的全部数据,表还在
delete from table_name
DELETE FROM Person WHERE age> 20
–删除数据还原标识
truncate table table_name
–添加Insert
给可以给字段默认值，如果Guid类型主键的默认值设定为newid()就会自动生成主键：
insert into Person3(Name,Age) values(’lili’,38);
insert into Person(Id,Name,Age) values(newid(),’tom’,30);
–更新Update
更新一个列:UPDATE T_Person Set Age=30
更新多个列:UPDATE T_Person Set Age=30,Name=‘tom’
更新一部分数据： UPDATE T_Person Set Age=30 where Name=‘tom’
——注意SQL中等于判断用单个=，而不是==
–Where中还可以使用复杂的逻辑判断UPDATE T_Person Set Age=30 where Name=‘tom’ or Age<25，
–or相当于C#中的||（或者）
update Person1 set NickName=N’二十岁’
where (Age>20 and Age<30) or(Age=80)
–Where中可以使用的其他逻辑运算符：or、and、not、<、>、>=、<=、!=（或<>）等
